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  • Direct Carbohydrate Analysis in Beverages and Foods Using Pulsed Amperometric Detection or Charged Aerosol Detection

    Qi Zhang, Bruce Bailey, Dave Thomas, Marc Plante, and Ian Acworth Thermo Fisher Scientific, Chelmsford, MA, USA

  • 2 Direct Carbohydrate Analysis in Beverages and Foods Using Pulsed Amperometric Detection or Charged Aerosol Detection

    Direct Carbohydrate Analysis in Beverages and Foods Using Pulsed Amperometric Detection or Charged Aerosol Detection Qi Zhang, Bruce Bailey, Dave Thomas, Marc Plante, and Ian Acworth Thermo Fisher Scientific, 22 Alpha Road, Chelmsford, MA, USA

    Overview Purpose: To develop simple direct methods for carbohydrate analysis in food and beverage without requirement for sample derivatization. Two approaches are discussed for direct analysis of carbohydrates in various food matrices, high performance liquid chromatography with pulsed amperometric detection (HPLC-PAD) and high performance liquid chromatography with charged aerosol detection (HPLC-CAD).

    Methods: Three HPLC-PAD methods were developed using ion exchange chromatography, including one isocratic method for simple sugar analysis in fruit juice, soda and syrups, one method for lactose and lactulose analysis in milk, and one gradient method for carbohydrate profiling of beer. Two HPLC-CAD methods using HILIC chromatography are also discussed for carbohydrate analysis in fruit juice and a sports beverage.

    Results: These methods enable rapid separation and reliable determination of carbohydrates in various foods and beverages with simple sample preparation and minimal matrix interference.

    Introduction Carbohydrates are important food components affecting taste and nutrition. The determination of the types and levels of carbohydrates in foods is important for energy evaluation, nutritional labeling, and quality control and for identifying possible product adulteration.

    Separation and detection of carbohydrates can be challenging. Simple carbohydrates are highly polar, uncharged, and as they lack a chromophore cannot be measured directly by UV absorbance detectors. HPLC with various detection techniques has been used for carbohydrate analysis, such as IR, mass spectrometry, UV or fluorescence following derivatization. Although methods utilize derivatization improve the chromatographic resolution and detector sensitivity, they can lead to increased assay variability. This poster presents two approaches for direct carbohydrate analysis, HPLC-PAD and HPLC-CAD, which solve the challenges for separation and detection without requirement for derivatization.

    Thermo Scientific™ Dionex™ UltiMate™ 3000 Electrochemical Detector now with PAD capabilities when coupled with a gold working electrode provides high sensitivity and selectivity for the measurement of carbohydrates in complex food sample matrices. Thermo Scientific™ Dionex™ Corona™ Charged Aerosol Detector is a mass-sensitive detector that can measure all non-volatile, and many semi-volatile compounds in a sample, typically with low nanogram sensitivity. Application examples for various juice samples, milk, beer, syrup and sport beverage will be discussed.

    Methods General Considerations for Pulsed Amperometric Detection The Thermo Scientific Dionex UltiMate 3000 LC system with PAD platform consisted of a base-compatible HPLC system, a Thermo UltiMate 3000 ECD-3000RS electrochemical detector and a gold working electrode. Carbohydrates were separated using ion exchange and determined under basic conditions using a four-pulse waveform. It is essential to make sure no titanium is in the flow path as its degradation under basic conditions can lead to deterioration of column and electrode performance. To prevent carbonate formation, all mobile phase should be kept under helium spurge or blanketed under helium gas. Carbohydrate Analysis by HPLC-PAD System:

    Mobile phase: 80 mM sodium hydroxide Flow rate: 1.5 mL/min Injection olume: 25 L Sample preparation:

    Cola soda: 1:1000 dilution in DI water Fruit juice: 1:1000 dilution in DI water, for juice with pulp, centrifuge and filter with 0.2 m filter before dilution Syrup: 100 g/mL dillution in DI water

    Column: Thermo Scientific™ Accucore™ 150-Amide-HILIC, 2.1 x 150 mm, 2.6 m

    Mobile phase: 6% 250 mM ammonium formate, 87% acetonitrile, 7% DI water Flow rate: 0.8mL/min Temperature: 75°C Inj. volume: 3 L Detector: Thermo Scientific™ Dionex™ Corona™ Veo™ SD (evaporator

    temperature high) Sample Preparation:

    Centrifuge with 0.2 m centrifuge filter at 13,000 rpm, 1:100 dilution in DI water, then 1:10 dilution in acetonitrile

    Results and Discussion

    FIGURE 1. Separation of seven common simple food carbohydrates with HPLC-PAD

    Carbohydrates are weak acids, and they are ionized when high pH mobile phase conditions are used. This allows for their separation by anion exchange chromatography, followed by sensitive and direct detection using pulsed amperometric detection. PAD is much more sensitive than UV and refractive index and its sensitivity is comparable to fluorescence detection. It is a very selective and specific detection mode since interferences from sample matrix become invisible to the detector, making sample preparation for many applications as simple as diluting the matrix with deionized water. The reproducibility of detection is enhanced by using a four pulse waveform that keeps the electrode surface clean even when complex samples are injected on the HPLC column. A rapid method for separation of seven simple carbohydrates commonly found in foods and beverages is shown in Figure 1. Simple sugars were completely separated with good resolution within 12 minutes. Figure 2 shows application of this method to fruit juice and soda samples. Several different types of syrup samples are shown in Figure 3 demonstrating the versatility of this HPLC-PAD method. All samples were simply diluted in DI water prior to injection.

    Direct Carbohydrate Analysis with HPLC-PAD

    FIGURE 2. Carbohydrate analysis in fruit juice and cola soda with HPLC-PAD

    FIGURE 4. Lactose and lactulose analysis in milk with HPLC-PAD

    Figure 5 shows a gradient HPLC-PAD method for profiling carbohydrates in beer. This method uses sodium acetate in addition to sodium hydroxide to increase the mobile phase strength to reduce the retention of oligosaccharides. This method allows for separation of malto-oligosaccharides up to DP13-15, as well as separation of some DP≤3 simple sugars such as glucose, fructose, sucrose and maltose, which enables carbohydrate profiling of different types of beer. Three different beers were analyzed, including a double chocolate stout, a Guinness extra stout, and a wheat beer and their carbohydrate profiles are compared in Figure 5.

    FIGURE 5. Carbohydrate profiling for beer with HPLC-PAD method.

    FIGURE 6. Analysis of carbohydrates in various fruit juice sampleswith HPLC- CAD using a Amide-HILIC column.

    FIGURE 7. Carbohydrate and electrolyte analysis of a sports beverage with HPLC-CAD.

    Conclusions

    • Both HPLC-PAD and HPLC-CAD provide simple, direct methods for carbohydrate analysis without the need for sample derivatization. Three HPLC-PAD methods using ion-exchange chromatography for carbohydrate analysis in fruit juice, soda, syrups and milk, as well as an gradient HPLC-PAD method for beer carbohydrate profiling were discussed. Two HPLC-CAD methods using HILIC chromatography are also discussed for carbohydrate analysis in fruit juice and a sports beverage.

    • Pulsed amperometric detection is highly sensitive and selective. Sample preparation can be as simple as dilution in water.

    • Electrochemical detection in DC mode can be used for other food components such as antioxidants, vitamins and amino acids.

    • Charged aerosol detector is a universal mass sensitive detector, and can be used for measurement of any nonvolatile and many semi-volatile analytes. Charged aerosol detection is applicable to many food. This includes antioxidants, amino acids, lipids, proteins, peptides, surfactants, artificial sweeteners, dyes, preservatives and emulsifiers.

    All trademarks are the property of Thermo Fisher Scientific and its subsidiaries. This information is not intended to encourage use of these products in any manners that might infringe the intellectual property rights of others. PO71524-EN 0315S

    Pump: ISO-3100 SD or LPG-3400SD Autosampler: WPS-3000TSL Analytical Autosampler Column: Anion exchange, 4.1 x 250 mm, 7m Temperature: 30 °C EC detector: EC-3000RS with 6041RS sensor and gold target EC Parameters: E1 +200 mV 500 ms AD 300 ms

    E2 -2000 mV 10 ms E3 +600 mV 10 ms E4 -100 mV 10 ms

    HPLC-PAD Method for Simple Sugar Analysis in Fruit Juice, Cola Soda, and Syrup

    HPLC-CAD Method for a Sport Beverage

    HPLC-PAD Method for Lactose and Lactulose Analysis in Milk

    Mobile phase A: 20 mM NaOH Mobile phase B: 200 mM NaOH Flow rate: 1.5 mL/min Gradient: 20 mM NaOH for 20 min, clean the column with 200 mM NaOH at end

    of run for 5 min, then equilibrate with 20 mM NaOH for 10 min Injection volume: 25 L Sample preparation:

    Protein precipitation with 1% perchloric acid at1:10 dilution, centrifuge, then dilute in DI water

    HPLC-PAD Method for Carbohydrate Analysis in Beer

    HPLC-CAD Method for Carbohydrate Analysis in Fruit Juice

    Mobile phase A: 100 mM sodium hydroxide Mobile phase B: 1 M NaOAc in 100 mM NaOH Flow rate: 1.5 mL/min Gradient: 100 mM NaOH for 2 mins, then 100% A to 30% B in 58min,

    gradient curve 6 Injection volume: 20 L Sample preparation:

    1:10 dilution in DI water

    Column: Thermo Scientific™ Acclaim™ Trinity™ P2, 3 x 50mm, 3 m Mobile phase: 20% 100mM ammonium formate at pH 3.65, 80% acetonitrile Flow rate: 0.6 mL/min Temperature: 50°C Inj. volume: 5 L Detector: Corona Veo RS, evaporator 55 °C Sample Preparation:

    Decolorize with Thermo Scientific™ Dionex™ OnGuard™ II P cartridge, dilute 1:40 in mobile phase

    FIGURE 3. Carbohydrate analysis in syrups with HPLC-PAD

    The global prevalence of lactose intolerance has created a large market for lactose-free products and the need for a simple, reliable and accurate method for determination of lactose in milk and other dairy products. The level of lactulose, which is formed by isomerization of lactose during the heat treatment of milk, can be used as an indicator to differentiate milk of different pasteurization or sterilization processes. The AOAC enzymatic method for lactose determination is time consuming and needs extensive reagent preparation. Figure 4 shows a simple HPLC-PAD method for determination of lactose and lactulose in milk within 35 minutes cycle time and requires minimal sample preparation.

    Direct Carbohydrate Analysis with HPLC-CAD

    HPLC with charged aerosol detection is another direct method for carbohydrate analysis. HILIC chromatography is utilized for separation of carbohydrates prior to CAD detection. Charged aerosol detection is a universal detection technique. It allows detection of any non-volatile and many semi-volatile samples independent of analyte chemical structure. Figure 6 shows separation of carbohydrates in various fruit juices on an Accucore Amide 150 column. This column provides excellent resolution and speed of separation of the various carbohydrate species when using decreased amounts of water along with elevated column temperatures. This provides the complete analysis of carbohydrates found in various beverages with a run time of only 6 minutes. Other food products such as honey and different corn syrups (data not shown) have also been successfully analyzed using HILIC chromatography methods with CAD detection. These techniques represent good examples of detecting analytes that possess weak or no chromophores using very simple analytical conditions and sample preparation.

    The method for simultaneous analysis of carbohydrates and electrolytes in a sports beverage shown in Figure 7 represents a good example of the universal character of Corona Veo. An Thermo ScientificTM DionexTM AcclaimTM TrinityTM P2 column was used in HILIC mode for separation in this method. Acclaim Trinity P2 columns offer cation-exchange, anion-exchange and HILIC retention mechanisms on the same phase. The ability of Trinity column to separate organic compounds, cations, and anions simultaneously, together with the universal detection of Corona Veo, allows for separation and detection of carbohydrates and the electrolyte chloride and sodium ions in a single run.

    Fruc

    tose

    G

    luco

    se

    Mal

    tose

    Chl

    orid

    e

    Sod

    ium

    Orange juice

    Apple juice

    Prune juice

    Grape juice

    Cola soda

    Standard

    Whole milk

    Fat free milk

    Lactose free milk

    Maple syrup

    Molasses

    Agave nectar

    Standard

    Grape juice

    Orange juice

    Apple juice

    Prune juice

    Double chocolate stout

    Wheat beer

    Guinness extra stout

    Standard

    0.00 1.00 2.00 3.00 4.00 5.00 6.00 -136

    -100

    -50

    0

    50

    74

    min

    pA

    0.1 10.0 20.0 30.0 40.0 50.0 60.0 -873 -750

    -500

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    0

    250

    500

    750

    957

    min

    nC

    0.0 2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0 -533

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    G a l

    a c t o

    s e

    G l u

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    l a c t

    o s e

    L a c

    t u l o

    s e

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    0.0 2.5 5.0 7.5 10.0 12.5 15.0 16.9 -361

    0

    500

    1,000

    1,179

    min

    nC

    0.0 2.0 4.0 6.0 8.0 10.0 12.0 -811

    -500

    -250

    0

    250

    589

    min

    nC

    0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 15.0 -84

    0

    200

    400

    600

    834

    min

    nC

  • 3Thermo Scienti� c Poster Note • PITTCON • PN71524-EN 0215S

    Direct Carbohydrate Analysis in Beverages and Foods Using Pulsed Amperometric Detection or Charged Aerosol Detection Qi Zhang, Bruce Bailey, Dave Thomas, Marc Plante, and Ian Acworth Thermo Fisher Scientific, 22 Alpha Road, Chelmsford, MA, USA

    Overview Purpose: To develop simple direct methods for carbohydrate analysis in food and beverage without requirement for sample derivatization. Two approaches are discussed for direct analysis of carbohydrates in various food matrices, high performance liquid chromatography with pulsed amperometric detection (HPLC-PAD) and high performance liquid chromatography with charged aerosol detection (HPLC-CAD).

    Methods: Three HPLC-PAD methods were developed using ion exchange chromatography, including one isocratic method for simple sugar analysis in fruit juice, soda and syrups, one method for lactose and lactulose analysis in milk, and one gradient method for carbohydrate profiling of beer. Two HPLC-CAD methods using HILIC chromatography are also discussed for carbohydrate analysis in fruit juice and a sports beverage.

    Results: These methods enable rapid separation and reliable determination of carbohydrates in various foods and beverages with simple sample preparation and minimal matrix interference.

    Introduction Carbohydrates are important food components affecting taste and nutrition. The determination of the types and levels of carbohydrates in foods is important for energy evaluation, nutritional labeling, and quality control and for identifying possible product adulteration.

    Separation and detection of carbohydrates can be challenging. Simple carbohydrates are highly polar, uncharged, and as they lack a chromophore cannot be measured directly by UV absorbance detectors. HPLC with various detection techniques has been used for carbohydrate analysis, such as IR, mass spectrometry, UV or fluorescence following derivatization. Although methods utilize derivatization improve the chromatographic resolution and detector sensitivity, they can lead to increased assay variability. This poster presents two approaches for direct carbohydrate analysis, HPLC-PAD and HPLC-CAD, which solve the challenges for separation and detection without requirement for derivatization.

    Thermo Scientific™ Dionex™ UltiMate™ 3000 Electrochemical Detector now with PAD capabilities when coupled with a gold working electrode provides high sensitivity and selectivity for the measurement of carbohydrates in complex food sample matrices. Thermo Scientific™ Dionex™ Corona™ Charged Aerosol Detector is a mass-sensitive detector that can measure all non-volatile, and many semi-volatile compounds in a sample, typically with low nanogram sensitivity. Application examples for various juice samples, milk, beer, syrup and sport beverage will be discussed.

    Methods General Considerations for Pulsed Amperometric Detection The Thermo Scientific Dionex UltiMate 3000 LC system with PAD platform consisted of a base-compatible HPLC system, a Thermo UltiMate 3000 ECD-3000RS electrochemical detector and a gold working electrode. Carbohydrates were separated using ion exchange and determined under basic conditions using a four-pulse waveform. It is essential to make sure no titanium is in the flow path as its degradation under basic conditions can lead to deterioration of column and electrode performance. To prevent carbonate formation, all mobile phase should be kept under helium spurge or blanketed under helium gas. Carbohydrate Analysis by HPLC-PAD System:

    Mobile phase: 80 mM sodium hydroxide Flow rate: 1.5 mL/min Injection olume: 25 L Sample preparation:

    Cola soda: 1:1000 dilution in DI water Fruit juice: 1:1000 dilution in DI water, for juice with pulp, centrifuge and filter with 0.2 m filter before dilution Syrup: 100 g/mL dillution in DI water

    Column: Thermo Scientific™ Accucore™ 150-Amide-HILIC, 2.1 x 150 mm, 2.6 m

    Mobile phase: 6% 250 mM ammonium formate, 87% acetonitrile, 7% DI water Flow rate: 0.8mL/min Temperature: 75°C Inj. volume: 3 L Detector: Thermo Scientific™ Dionex™ Corona™ Veo™ SD (evaporator

    temperature high) Sample Preparation:

    Centrifuge with 0.2 m centrifuge filter at 13,000 rpm, 1:100 dilution in DI water, then 1:10 dilution in acetonitrile

    Results and Discussion

    FIGURE 1. Separation of seven common simple food carbohydrates with HPLC-PAD

    Carbohydrates are weak acids, and they are ionized when high pH mobile phase conditions are used. This allows for their separation by anion exchange chromatography, followed by sensitive and direct detection using pulsed amperometric detection. PAD is much more sensitive than UV and refractive index and its sensitivity is comparable to fluorescence detection. It is a very selective and specific detection mode since interferences from sample matrix become invisible to the detector, making sample preparation for many applications as simple as diluting the matrix with deionized water. The reproducibility of detection is enhanced by using a four pulse waveform that keeps the electrode surface clean even when complex samples are injected on the HPLC column. A rapid method for separation of seven simple carbohydrates commonly found in foods and beverages is shown in Figure 1. Simple sugars were completely separated with good resolution within 12 minutes. Figure 2 shows application of this method to fruit juice and soda samples. Several different types of syrup samples are shown in Figure 3 demonstrating the versatility of this HPLC-PAD method. All samples were simply diluted in DI water prior to injection.

    Direct Carbohydrate Analysis with HPLC-PAD

    FIGURE 2. Carbohydrate analysis in fruit juice and cola soda with HPLC-PAD

    FIGURE 4. Lactose and lactulose analysis in milk with HPLC-PAD

    Figure 5 shows a gradient HPLC-PAD method for profiling carbohydrates in beer. This method uses sodium acetate in addition to sodium hydroxide to increase the mobile phase strength to reduce the retention of oligosaccharides. This method allows for separation of malto-oligosaccharides up to DP13-15, as well as separation of some DP≤3 simple sugars such as glucose, fructose, sucrose and maltose, which enables carbohydrate profiling of different types of beer. Three different beers were analyzed, including a double chocolate stout, a Guinness extra stout, and a wheat beer and their carbohydrate profiles are compared in Figure 5.

    FIGURE 5. Carbohydrate profiling for beer with HPLC-PAD method.

    FIGURE 6. Analysis of carbohydrates in various fruit juice sampleswith HPLC- CAD using a Amide-HILIC column.

    FIGURE 7. Carbohydrate and electrolyte analysis of a sports beverage with HPLC-CAD.

    Conclusions

    • Both HPLC-PAD and HPLC-CAD provide simple, direct methods for carbohydrate analysis without the need for sample derivatization. Three HPLC-PAD methods using ion-exchange chromatography for carbohydrate analysis in fruit juice, soda, syrups and milk, as well as an gradient HPLC-PAD method for beer carbohydrate profiling were discussed. Two HPLC-CAD methods using HILIC chromatography are also discussed for carbohydrate analysis in fruit juice and a sports beverage.

    • Pulsed amperometric detection is highly sensitive and selective. Sample preparation can be as simple as dilution in water.

    • Electrochemical detection in DC mode can be used for other food components such as antioxidants, vitamins and amino acids.

    • Charged aerosol detector is a universal mass sensitive detector, and can be used for measurement of any nonvolatile and many semi-volatile analytes. Charged aerosol detection is applicable to many food. This includes antioxidants, amino acids, lipids, proteins, peptides, surfactants, artificial sweeteners, dyes, preservatives and emulsifiers.

    All trademarks are the property of Thermo Fisher Scientific and its subsidiaries. This information is not intended to encourage use of these products in any manners that might infringe the intellectual property rights of others. PO71524-EN 0315S

    Pump: ISO-3100 SD or LPG-3400SD Autosampler: WPS-3000TSL Analytical Autosampler Column: Anion exchange, 4.1 x 250 mm, 7m Temperature: 30 °C EC detector: EC-3000RS with 6041RS sensor and gold target EC Parameters: E1 +200 mV 500 ms AD 300 ms

    E2 -2000 mV 10 ms E3 +600 mV 10 ms E4 -100 mV 10 ms

    HPLC-PAD Method for Simple Sugar Analysis in Fruit Juice, Cola Soda, and Syrup

    HPLC-CAD Method for a Sport Beverage

    HPLC-PAD Method for Lactose and Lactulose Analysis in Milk

    Mobile phase A: 20 mM NaOH Mobile phase B: 200 mM NaOH Flow rate: 1.5 mL/min Gradient: 20 mM NaOH for 20 min, clean the column with 200 mM NaOH at end

    of run for 5 min, then equilibrate with 20 mM NaOH for 10 min Injection volume: 25 L Sample preparation:

    Protein precipitation with 1% perchloric acid at1:10 dilution, centrifuge, then dilute in DI water

    HPLC-PAD Method for Carbohydrate Analysis in Beer

    HPLC-CAD Method for Carbohydrate Analysis in Fruit Juice

    Mobile phase A: 100 mM sodium hydroxide Mobile phase B: 1 M NaOAc in 100 mM NaOH Flow rate: 1.5 mL/min Gradient: 100 mM NaOH for 2 mins, then 100% A to 30% B in 58min,

    gradient curve 6 Injection volume: 20 L Sample preparation:

    1:10 dilution in DI water

    Column: Thermo Scientific™ Acclaim™ Trinity™ P2, 3 x 50mm, 3 m Mobile phase: 20% 100mM ammonium formate at pH 3.65, 80% acetonitrile Flow rate: 0.6 mL/min Temperature: 50°C Inj. volume: 5 L Detector: Corona Veo RS, evaporator 55 °C Sample Preparation:

    Decolorize with Thermo Scientific™ Dionex™ OnGuard™ II P cartridge, dilute 1:40 in mobile phase

    FIGURE 3. Carbohydrate analysis in syrups with HPLC-PAD

    The global prevalence of lactose intolerance has created a large market for lactose-free products and the need for a simple, reliable and accurate method for determination of lactose in milk and other dairy products. The level of lactulose, which is formed by isomerization of lactose during the heat treatment of milk, can be used as an indicator to differentiate milk of different pasteurization or sterilization processes. The AOAC enzymatic method for lactose determination is time consuming and needs extensive reagent preparation. Figure 4 shows a simple HPLC-PAD method for determination of lactose and lactulose in milk within 35 minutes cycle time and requires minimal sample preparation.

    Direct Carbohydrate Analysis with HPLC-CAD

    HPLC with charged aerosol detection is another direct method for carbohydrate analysis. HILIC chromatography is utilized for separation of carbohydrates prior to CAD detection. Charged aerosol detection is a universal detection technique. It allows detection of any non-volatile and many semi-volatile samples independent of analyte chemical structure. Figure 6 shows separation of carbohydrates in various fruit juices on an Accucore Amide 150 column. This column provides excellent resolution and speed of separation of the various carbohydrate species when using decreased amounts of water along with elevated column temperatures. This provides the complete analysis of carbohydrates found in various beverages with a run time of only 6 minutes. Other food products such as honey and different corn syrups (data not shown) have also been successfully analyzed using HILIC chromatography methods with CAD detection. These techniques represent good examples of detecting analytes that possess weak or no chromophores using very simple analytical conditions and sample preparation.

    The method for simultaneous analysis of carbohydrates and electrolytes in a sports beverage shown in Figure 7 represents a good example of the universal character of Corona Veo. An Thermo ScientificTM DionexTM AcclaimTM TrinityTM P2 column was used in HILIC mode for separation in this method. Acclaim Trinity P2 columns offer cation-exchange, anion-exchange and HILIC retention mechanisms on the same phase. The ability of Trinity column to separate organic compounds, cations, and anions simultaneously, together with the universal detection of Corona Veo, allows for separation and detection of carbohydrates and the electrolyte chloride and sodium ions in a single run.

    Fruc

    tose

    G

    luco

    se

    Mal

    tose

    Chl

    orid

    e

    Sod

    ium

    Orange juice

    Apple juice

    Prune juice

    Grape juice

    Cola soda

    Standard

    Whole milk

    Fat free milk

    Lactose free milk

    Maple syrup

    Molasses

    Agave nectar

    Standard

    Grape juice

    Orange juice

    Apple juice

    Prune juice

    Double chocolate stout

    Wheat beer

    Guinness extra stout

    Standard

    0.00 1.00 2.00 3.00 4.00 5.00 6.00 -136

    -100

    -50

    0

    50

    74

    min

    pA

    0.1 10.0 20.0 30.0 40.0 50.0 60.0 -873 -750

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    500

    750

    957

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    0.0 2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0 -533

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    0.0 2.5 5.0 7.5 10.0 12.5 15.0 16.9 -361

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    1,000

    1,179

    min

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    0.0 2.0 4.0 6.0 8.0 10.0 12.0 -811

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    834

    min

    nC

  • 4 Direct Carbohydrate Analysis in Beverages and Foods Using Pulsed Amperometric Detection or Charged Aerosol Detection

    Direct Carbohydrate Analysis in Beverages and Foods Using Pulsed Amperometric Detection or Charged Aerosol Detection Qi Zhang, Bruce Bailey, Dave Thomas, Marc Plante, and Ian Acworth Thermo Fisher Scientific, 22 Alpha Road, Chelmsford, MA, USA

    Overview Purpose: To develop simple direct methods for carbohydrate analysis in food and beverage without requirement for sample derivatization. Two approaches are discussed for direct analysis of carbohydrates in various food matrices, high performance liquid chromatography with pulsed amperometric detection (HPLC-PAD) and high performance liquid chromatography with charged aerosol detection (HPLC-CAD).

    Methods: Three HPLC-PAD methods were developed using ion exchange chromatography, including one isocratic method for simple sugar analysis in fruit juice, soda and syrups, one method for lactose and lactulose analysis in milk, and one gradient method for carbohydrate profiling of beer. Two HPLC-CAD methods using HILIC chromatography are also discussed for carbohydrate analysis in fruit juice and a sports beverage.

    Results: These methods enable rapid separation and reliable determination of carbohydrates in various foods and beverages with simple sample preparation and minimal matrix interference.

    Introduction Carbohydrates are important food components affecting taste and nutrition. The determination of the types and levels of carbohydrates in foods is important for energy evaluation, nutritional labeling, and quality control and for identifying possible product adulteration.

    Separation and detection of carbohydrates can be challenging. Simple carbohydrates are highly polar, uncharged, and as they lack a chromophore cannot be measured directly by UV absorbance detectors. HPLC with various detection techniques has been used for carbohydrate analysis, such as IR, mass spectrometry, UV or fluorescence following derivatization. Although methods utilize derivatization improve the chromatographic resolution and detector sensitivity, they can lead to increased assay variability. This poster presents two approaches for direct carbohydrate analysis, HPLC-PAD and HPLC-CAD, which solve the challenges for separation and detection without requirement for derivatization.

    Thermo Scientific™ Dionex™ UltiMate™ 3000 Electrochemical Detector now with PAD capabilities when coupled with a gold working electrode provides high sensitivity and selectivity for the measurement of carbohydrates in complex food sample matrices. Thermo Scientific™ Dionex™ Corona™ Charged Aerosol Detector is a mass-sensitive detector that can measure all non-volatile, and many semi-volatile compounds in a sample, typically with low nanogram sensitivity. Application examples for various juice samples, milk, beer, syrup and sport beverage will be discussed.

    Methods General Considerations for Pulsed Amperometric Detection The Thermo Scientific Dionex UltiMate 3000 LC system with PAD platform consisted of a base-compatible HPLC system, a Thermo UltiMate 3000 ECD-3000RS electrochemical detector and a gold working electrode. Carbohydrates were separated using ion exchange and determined under basic conditions using a four-pulse waveform. It is essential to make sure no titanium is in the flow path as its degradation under basic conditions can lead to deterioration of column and electrode performance. To prevent carbonate formation, all mobile phase should be kept under helium spurge or blanketed under helium gas. Carbohydrate Analysis by HPLC-PAD System:

    Mobile phase: 80 mM sodium hydroxide Flow rate: 1.5 mL/min Injection olume: 25 L Sample preparation:

    Cola soda: 1:1000 dilution in DI water Fruit juice: 1:1000 dilution in DI water, for juice with pulp, centrifuge and filter with 0.2 m filter before dilution Syrup: 100 g/mL dillution in DI water

    Column: Thermo Scientific™ Accucore™ 150-Amide-HILIC, 2.1 x 150 mm, 2.6 m

    Mobile phase: 6% 250 mM ammonium formate, 87% acetonitrile, 7% DI water Flow rate: 0.8mL/min Temperature: 75°C Inj. volume: 3 L Detector: Thermo Scientific™ Dionex™ Corona™ Veo™ SD (evaporator

    temperature high) Sample Preparation:

    Centrifuge with 0.2 m centrifuge filter at 13,000 rpm, 1:100 dilution in DI water, then 1:10 dilution in acetonitrile

    Results and Discussion

    FIGURE 1. Separation of seven common simple food carbohydrates with HPLC-PAD

    Carbohydrates are weak acids, and they are ionized when high pH mobile phase conditions are used. This allows for their separation by anion exchange chromatography, followed by sensitive and direct detection using pulsed amperometric detection. PAD is much more sensitive than UV and refractive index and its sensitivity is comparable to fluorescence detection. It is a very selective and specific detection mode since interferences from sample matrix become invisible to the detector, making sample preparation for many applications as simple as diluting the matrix with deionized water. The reproducibility of detection is enhanced by using a four pulse waveform that keeps the electrode surface clean even when complex samples are injected on the HPLC column. A rapid method for separation of seven simple carbohydrates commonly found in foods and beverages is shown in Figure 1. Simple sugars were completely separated with good resolution within 12 minutes. Figure 2 shows application of this method to fruit juice and soda samples. Several different types of syrup samples are shown in Figure 3 demonstrating the versatility of this HPLC-PAD method. All samples were simply diluted in DI water prior to injection.

    Direct Carbohydrate Analysis with HPLC-PAD

    FIGURE 2. Carbohydrate analysis in fruit juice and cola soda with HPLC-PAD

    FIGURE 4. Lactose and lactulose analysis in milk with HPLC-PAD

    Figure 5 shows a gradient HPLC-PAD method for profiling carbohydrates in beer. This method uses sodium acetate in addition to sodium hydroxide to increase the mobile phase strength to reduce the retention of oligosaccharides. This method allows for separation of malto-oligosaccharides up to DP13-15, as well as separation of some DP≤3 simple sugars such as glucose, fructose, sucrose and maltose, which enables carbohydrate profiling of different types of beer. Three different beers were analyzed, including a double chocolate stout, a Guinness extra stout, and a wheat beer and their carbohydrate profiles are compared in Figure 5.

    FIGURE 5. Carbohydrate profiling for beer with HPLC-PAD method.

    FIGURE 6. Analysis of carbohydrates in various fruit juice sampleswith HPLC- CAD using a Amide-HILIC column.

    FIGURE 7. Carbohydrate and electrolyte analysis of a sports beverage with HPLC-CAD.

    Conclusions

    • Both HPLC-PAD and HPLC-CAD provide simple, direct methods for carbohydrate analysis without the need for sample derivatization. Three HPLC-PAD methods using ion-exchange chromatography for carbohydrate analysis in fruit juice, soda, syrups and milk, as well as an gradient HPLC-PAD method for beer carbohydrate profiling were discussed. Two HPLC-CAD methods using HILIC chromatography are also discussed for carbohydrate analysis in fruit juice and a sports beverage.

    • Pulsed amperometric detection is highly sensitive and selective. Sample preparation can be as simple as dilution in water.

    • Electrochemical detection in DC mode can be used for other food components such as antioxidants, vitamins and amino acids.

    • Charged aerosol detector is a universal mass sensitive detector, and can be used for measurement of any nonvolatile and many semi-volatile analytes. Charged aerosol detection is applicable to many food. This includes antioxidants, amino acids, lipids, proteins, peptides, surfactants, artificial sweeteners, dyes, preservatives and emulsifiers.

    All trademarks are the property of Thermo Fisher Scientific and its subsidiaries. This information is not intended to encourage use of these products in any manners that might infringe the intellectual property rights of others. PO71524-EN 0315S

    Pump: ISO-3100 SD or LPG-3400SD Autosampler: WPS-3000TSL Analytical Autosampler Column: Anion exchange, 4.1 x 250 mm, 7m Temperature: 30 °C EC detector: EC-3000RS with 6041RS sensor and gold target EC Parameters: E1 +200 mV 500 ms AD 300 ms

    E2 -2000 mV 10 ms E3 +600 mV 10 ms E4 -100 mV 10 ms

    HPLC-PAD Method for Simple Sugar Analysis in Fruit Juice, Cola Soda, and Syrup

    HPLC-CAD Method for a Sport Beverage

    HPLC-PAD Method for Lactose and Lactulose Analysis in Milk

    Mobile phase A: 20 mM NaOH Mobile phase B: 200 mM NaOH Flow rate: 1.5 mL/min Gradient: 20 mM NaOH for 20 min, clean the column with 200 mM NaOH at end

    of run for 5 min, then equilibrate with 20 mM NaOH for 10 min Injection volume: 25 L Sample preparation:

    Protein precipitation with 1% perchloric acid at1:10 dilution, centrifuge, then dilute in DI water

    HPLC-PAD Method for Carbohydrate Analysis in Beer

    HPLC-CAD Method for Carbohydrate Analysis in Fruit Juice

    Mobile phase A: 100 mM sodium hydroxide Mobile phase B: 1 M NaOAc in 100 mM NaOH Flow rate: 1.5 mL/min Gradient: 100 mM NaOH for 2 mins, then 100% A to 30% B in 58min,

    gradient curve 6 Injection volume: 20 L Sample preparation:

    1:10 dilution in DI water

    Column: Thermo Scientific™ Acclaim™ Trinity™ P2, 3 x 50mm, 3 m Mobile phase: 20% 100mM ammonium formate at pH 3.65, 80% acetonitrile Flow rate: 0.6 mL/min Temperature: 50°C Inj. volume: 5 L Detector: Corona Veo RS, evaporator 55 °C Sample Preparation:

    Decolorize with Thermo Scientific™ Dionex™ OnGuard™ II P cartridge, dilute 1:40 in mobile phase

    FIGURE 3. Carbohydrate analysis in syrups with HPLC-PAD

    The global prevalence of lactose intolerance has created a large market for lactose-free products and the need for a simple, reliable and accurate method for determination of lactose in milk and other dairy products. The level of lactulose, which is formed by isomerization of lactose during the heat treatment of milk, can be used as an indicator to differentiate milk of different pasteurization or sterilization processes. The AOAC enzymatic method for lactose determination is time consuming and needs extensive reagent preparation. Figure 4 shows a simple HPLC-PAD method for determination of lactose and lactulose in milk within 35 minutes cycle time and requires minimal sample preparation.

    Direct Carbohydrate Analysis with HPLC-CAD

    HPLC with charged aerosol detection is another direct method for carbohydrate analysis. HILIC chromatography is utilized for separation of carbohydrates prior to CAD detection. Charged aerosol detection is a universal detection technique. It allows detection of any non-volatile and many semi-volatile samples independent of analyte chemical structure. Figure 6 shows separation of carbohydrates in various fruit juices on an Accucore Amide 150 column. This column provides excellent resolution and speed of separation of the various carbohydrate species when using decreased amounts of water along with elevated column temperatures. This provides the complete analysis of carbohydrates found in various beverages with a run time of only 6 minutes. Other food products such as honey and different corn syrups (data not shown) have also been successfully analyzed using HILIC chromatography methods with CAD detection. These techniques represent good examples of detecting analytes that possess weak or no chromophores using very simple analytical conditions and sample preparation.

    The method for simultaneous analysis of carbohydrates and electrolytes in a sports beverage shown in Figure 7 represents a good example of the universal character of Corona Veo. An Thermo ScientificTM DionexTM AcclaimTM TrinityTM P2 column was used in HILIC mode for separation in this method. Acclaim Trinity P2 columns offer cation-exchange, anion-exchange and HILIC retention mechanisms on the same phase. The ability of Trinity column to separate organic compounds, cations, and anions simultaneously, together with the universal detection of Corona Veo, allows for separation and detection of carbohydrates and the electrolyte chloride and sodium ions in a single run.

    Fruc

    tose

    G

    luco

    se

    Mal

    tose

    Chl

    orid

    e

    Sod

    ium

    Orange juice

    Apple juice

    Prune juice

    Grape juice

    Cola soda

    Standard

    Whole milk

    Fat free milk

    Lactose free milk

    Maple syrup

    Molasses

    Agave nectar

    Standard

    Grape juice

    Orange juice

    Apple juice

    Prune juice

    Double chocolate stout

    Wheat beer

    Guinness extra stout

    Standard

    0.00 1.00 2.00 3.00 4.00 5.00 6.00 -136

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    -50

    0

    50

    74

    min

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    0.1 10.0 20.0 30.0 40.0 50.0 60.0 -873 -750

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    0

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  • 5Thermo Scienti� c Poster Note • PITTCON • PN71524-EN 0215S

    Direct Carbohydrate Analysis in Beverages and Foods Using Pulsed Amperometric Detection or Charged Aerosol Detection Qi Zhang, Bruce Bailey, Dave Thomas, Marc Plante, and Ian Acworth Thermo Fisher Scientific, 22 Alpha Road, Chelmsford, MA, USA

    Overview Purpose: To develop simple direct methods for carbohydrate analysis in food and beverage without requirement for sample derivatization. Two approaches are discussed for direct analysis of carbohydrates in various food matrices, high performance liquid chromatography with pulsed amperometric detection (HPLC-PAD) and high performance liquid chromatography with charged aerosol detection (HPLC-CAD).

    Methods: Three HPLC-PAD methods were developed using ion exchange chromatography, including one isocratic method for simple sugar analysis in fruit juice, soda and syrups, one method for lactose and lactulose analysis in milk, and one gradient method for carbohydrate profiling of beer. Two HPLC-CAD methods using HILIC chromatography are also discussed for carbohydrate analysis in fruit juice and a sports beverage.

    Results: These methods enable rapid separation and reliable determination of carbohydrates in various foods and beverages with simple sample preparation and minimal matrix interference.

    Introduction Carbohydrates are important food components affecting taste and nutrition. The determination of the types and levels of carbohydrates in foods is important for energy evaluation, nutritional labeling, and quality control and for identifying possible product adulteration.

    Separation and detection of carbohydrates can be challenging. Simple carbohydrates are highly polar, uncharged, and as they lack a chromophore cannot be measured directly by UV absorbance detectors. HPLC with various detection techniques has been used for carbohydrate analysis, such as IR, mass spectrometry, UV or fluorescence following derivatization. Although methods utilize derivatization improve the chromatographic resolution and detector sensitivity, they can lead to increased assay variability. This poster presents two approaches for direct carbohydrate analysis, HPLC-PAD and HPLC-CAD, which solve the challenges for separation and detection without requirement for derivatization.

    Thermo Scientific™ Dionex™ UltiMate™ 3000 Electrochemical Detector now with PAD capabilities when coupled with a gold working electrode provides high sensitivity and selectivity for the measurement of carbohydrates in complex food sample matrices. Thermo Scientific™ Dionex™ Corona™ Charged Aerosol Detector is a mass-sensitive detector that can measure all non-volatile, and many semi-volatile compounds in a sample, typically with low nanogram sensitivity. Application examples for various juice samples, milk, beer, syrup and sport beverage will be discussed.

    Methods General Considerations for Pulsed Amperometric Detection The Thermo Scientific Dionex UltiMate 3000 LC system with PAD platform consisted of a base-compatible HPLC system, a Thermo UltiMate 3000 ECD-3000RS electrochemical detector and a gold working electrode. Carbohydrates were separated using ion exchange and determined under basic conditions using a four-pulse waveform. It is essential to make sure no titanium is in the flow path as its degradation under basic conditions can lead to deterioration of column and electrode performance. To prevent carbonate formation, all mobile phase should be kept under helium spurge or blanketed under helium gas. Carbohydrate Analysis by HPLC-PAD System:

    Mobile phase: 80 mM sodium hydroxide Flow rate: 1.5 mL/min Injection olume: 25 L Sample preparation:

    Cola soda: 1:1000 dilution in DI water Fruit juice: 1:1000 dilution in DI water, for juice with pulp, centrifuge and filter with 0.2 m filter before dilution Syrup: 100 g/mL dillution in DI water

    Column: Thermo Scientific™ Accucore™ 150-Amide-HILIC, 2.1 x 150 mm, 2.6 m

    Mobile phase: 6% 250 mM ammonium formate, 87% acetonitrile, 7% DI water Flow rate: 0.8mL/min Temperature: 75°C Inj. volume: 3 L Detector: Thermo Scientific™ Dionex™ Corona™ Veo™ SD (evaporator

    temperature high) Sample Preparation:

    Centrifuge with 0.2 m centrifuge filter at 13,000 rpm, 1:100 dilution in DI water, then 1:10 dilution in acetonitrile

    Results and Discussion

    FIGURE 1. Separation of seven common simple food carbohydrates with HPLC-PAD

    Carbohydrates are weak acids, and they are ionized when high pH mobile phase conditions are used. This allows for their separation by anion exchange chromatography, followed by sensitive and direct detection using pulsed amperometric detection. PAD is much more sensitive than UV and refractive index and its sensitivity is comparable to fluorescence detection. It is a very selective and specific detection mode since interferences from sample matrix become invisible to the detector, making sample preparation for many applications as simple as diluting the matrix with deionized water. The reproducibility of detection is enhanced by using a four pulse waveform that keeps the electrode surface clean even when complex samples are injected on the HPLC column. A rapid method for separation of seven simple carbohydrates commonly found in foods and beverages is shown in Figure 1. Simple sugars were completely separated with good resolution within 12 minutes. Figure 2 shows application of this method to fruit juice and soda samples. Several different types of syrup samples are shown in Figure 3 demonstrating the versatility of this HPLC-PAD method. All samples were simply diluted in DI water prior to injection.

    Direct Carbohydrate Analysis with HPLC-PAD

    FIGURE 2. Carbohydrate analysis in fruit juice and cola soda with HPLC-PAD

    FIGURE 4. Lactose and lactulose analysis in milk with HPLC-PAD

    Figure 5 shows a gradient HPLC-PAD method for profiling carbohydrates in beer. This method uses sodium acetate in addition to sodium hydroxide to increase the mobile phase strength to reduce the retention of oligosaccharides. This method allows for separation of malto-oligosaccharides up to DP13-15, as well as separation of some DP≤3 simple sugars such as glucose, fructose, sucrose and maltose, which enables carbohydrate profiling of different types of beer. Three different beers were analyzed, including a double chocolate stout, a Guinness extra stout, and a wheat beer and their carbohydrate profiles are compared in Figure 5.

    FIGURE 5. Carbohydrate profiling for beer with HPLC-PAD method.

    FIGURE 6. Analysis of carbohydrates in various fruit juice sampleswith HPLC- CAD using a Amide-HILIC column.

    FIGURE 7. Carbohydrate and electrolyte analysis of a sports beverage with HPLC-CAD.

    Conclusions

    • Both HPLC-PAD and HPLC-CAD provide simple, direct methods for carbohydrate analysis without the need for sample derivatization. Three HPLC-PAD methods using ion-exchange chromatography for carbohydrate analysis in fruit juice, soda, syrups and milk, as well as an gradient HPLC-PAD method for beer carbohydrate profiling were discussed. Two HPLC-CAD methods using HILIC chromatography are also discussed for carbohydrate analysis in fruit juice and a sports beverage.

    • Pulsed amperometric detection is highly sensitive and selective. Sample preparation can be as simple as dilution in water.

    • Electrochemical detection in DC mode can be used for other food components such as antioxidants, vitamins and amino acids.

    • Charged aerosol detector is a universal mass sensitive detector, and can be used for measurement of any nonvolatile and many semi-volatile analytes. Charged aerosol detection is applicable to many food. This includes antioxidants, amino acids, lipids, proteins, peptides, surfactants, artificial sweeteners, dyes, preservatives and emulsifiers.

    All trademarks are the property of Thermo Fisher Scientific and its subsidiaries. This information is not intended to encourage use of these products in any manners that might infringe the intellectual property rights of others. PO71524-EN 0315S

    Pump: ISO-3100 SD or LPG-3400SD Autosampler: WPS-3000TSL Analytical Autosampler Column: Anion exchange, 4.1 x 250 mm, 7m Temperature: 30 °C EC detector: EC-3000RS with 6041RS sensor and gold target EC Parameters: E1 +200 mV 500 ms AD 300 ms

    E2 -2000 mV 10 ms E3 +600 mV 10 ms E4 -100 mV 10 ms

    HPLC-PAD Method for Simple Sugar Analysis in Fruit Juice, Cola Soda, and Syrup

    HPLC-CAD Method for a Sport Beverage

    HPLC-PAD Method for Lactose and Lactulose Analysis in Milk

    Mobile phase A: 20 mM NaOH Mobile phase B: 200 mM NaOH Flow rate: 1.5 mL/min Gradient: 20 mM NaOH for 20 min, clean the column with 200 mM NaOH at end

    of run for 5 min, then equilibrate with 20 mM NaOH for 10 min Injection volume: 25 L Sample preparation:

    Protein precipitation with 1% perchloric acid at1:10 dilution, centrifuge, then dilute in DI water

    HPLC-PAD Method for Carbohydrate Analysis in Beer

    HPLC-CAD Method for Carbohydrate Analysis in Fruit Juice

    Mobile phase A: 100 mM sodium hydroxide Mobile phase B: 1 M NaOAc in 100 mM NaOH Flow rate: 1.5 mL/min Gradient: 100 mM NaOH for 2 mins, then 100% A to 30% B in 58min,

    gradient curve 6 Injection volume: 20 L Sample preparation:

    1:10 dilution in DI water

    Column: Thermo Scientific™ Acclaim™ Trinity™ P2, 3 x 50mm, 3 m Mobile phase: 20% 100mM ammonium formate at pH 3.65, 80% acetonitrile Flow rate: 0.6 mL/min Temperature: 50°C Inj. volume: 5 L Detector: Corona Veo RS, evaporator 55 °C Sample Preparation:

    Decolorize with Thermo Scientific™ Dionex™ OnGuard™ II P cartridge, dilute 1:40 in mobile phase

    FIGURE 3. Carbohydrate analysis in syrups with HPLC-PAD

    The global prevalence of lactose intolerance has created a large market for lactose-free products and the need for a simple, reliable and accurate method for determination of lactose in milk and other dairy products. The level of lactulose, which is formed by isomerization of lactose during the heat treatment of milk, can be used as an indicator to differentiate milk of different pasteurization or sterilization processes. The AOAC enzymatic method for lactose determination is time consuming and needs extensive reagent preparation. Figure 4 shows a simple HPLC-PAD method for determination of lactose and lactulose in milk within 35 minutes cycle time and requires minimal sample preparation.

    Direct Carbohydrate Analysis with HPLC-CAD

    HPLC with charged aerosol detection is another direct method for carbohydrate analysis. HILIC chromatography is utilized for separation of carbohydrates prior to CAD detection. Charged aerosol detection is a universal detection technique. It allows detection of any non-volatile and many semi-volatile samples independent of analyte chemical structure. Figure 6 shows separation of carbohydrates in various fruit juices on an Accucore Amide 150 column. This column provides excellent resolution and speed of separation of the various carbohydrate species when using decreased amounts of water along with elevated column temperatures. This provides the complete analysis of carbohydrates found in various beverages with a run time of only 6 minutes. Other food products such as honey and different corn syrups (data not shown) have also been successfully analyzed using HILIC chromatography methods with CAD detection. These techniques represent good examples of detecting analytes that possess weak or no chromophores using very simple analytical conditions and sample preparation.

    The method for simultaneous analysis of carbohydrates and electrolytes in a sports beverage shown in Figure 7 represents a good example of the universal character of Corona Veo. An Thermo ScientificTM DionexTM AcclaimTM TrinityTM P2 column was used in HILIC mode for separation in this method. Acclaim Trinity P2 columns offer cation-exchange, anion-exchange and HILIC retention mechanisms on the same phase. The ability of Trinity column to separate organic compounds, cations, and anions simultaneously, together with the universal detection of Corona Veo, allows for separation and detection of carbohydrates and the electrolyte chloride and sodium ions in a single run.

    Fruc

    tose

    G

    luco

    se

    Mal

    tose

    Chl

    orid

    e

    Sod

    ium

    Orange juice

    Apple juice

    Prune juice

    Grape juice

    Cola soda

    Standard

    Whole milk

    Fat free milk

    Lactose free milk

    Maple syrup

    Molasses

    Agave nectar

    Standard

    Grape juice

    Orange juice

    Apple juice

    Prune juice

    Double chocolate stout

    Wheat beer

    Guinness extra stout

    Standard

    0.00 1.00 2.00 3.00 4.00 5.00 6.00 -136

    -100

    -50

    0

    50

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    0.1 10.0 20.0 30.0 40.0 50.0 60.0 -873 -750

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    834

    min

    nC

  • 6 Direct Carbohydrate Analysis in Beverages and Foods Using Pulsed Amperometric Detection or Charged Aerosol Detection

    Direct Carbohydrate Analysis in Beverages and Foods Using Pulsed Amperometric Detection or Charged Aerosol Detection Qi Zhang, Bruce Bailey, Dave Thomas, Marc Plante, and Ian Acworth Thermo Fisher Scientific, 22 Alpha Road, Chelmsford, MA, USA

    Overview Purpose: To develop simple direct methods for carbohydrate analysis in food and beverage without requirement for sample derivatization. Two approaches are discussed for direct analysis of carbohydrates in various food matrices, high performance liquid chromatography with pulsed amperometric detection (HPLC-PAD) and high performance liquid chromatography with charged aerosol detection (HPLC-CAD).

    Methods: Three HPLC-PAD methods were developed using ion exchange chromatography, including one isocratic method for simple sugar analysis in fruit juice, soda and syrups, one method for lactose and lactulose analysis in milk, and one gradient method for carbohydrate profiling of beer. Two HPLC-CAD methods using HILIC chromatography are also discussed for carbohydrate analysis in fruit juice and a sports beverage.

    Results: These methods enable rapid separation and reliable determination of carbohydrates in various foods and beverages with simple sample preparation and minimal matrix interference.

    Introduction Carbohydrates are important food components affecting taste and nutrition. The determination of the types and levels of carbohydrates in foods is important for energy evaluation, nutritional labeling, and quality control and for identifying possible product adulteration.

    Separation and detection of carbohydrates can be challenging. Simple carbohydrates are highly polar, uncharged, and as they lack a chromophore cannot be measured directly by UV absorbance detectors. HPLC with various detection techniques has been used for carbohydrate analysis, such as IR, mass spectrometry, UV or fluorescence following derivatization. Although methods utilize derivatization improve the chromatographic resolution and detector sensitivity, they can lead to increased assay variability. This poster presents two approaches for direct carbohydrate analysis, HPLC-PAD and HPLC-CAD, which solve the challenges for separation and detection without requirement for derivatization.

    Thermo Scientific™ Dionex™ UltiMate™ 3000 Electrochemical Detector now with PAD capabilities when coupled with a gold working electrode provides high sensitivity and selectivity for the measurement of carbohydrates in complex food sample matrices. Thermo Scientific™ Dionex™ Corona™ Charged Aerosol Detector is a mass-sensitive detector that can measure all non-volatile, and many semi-volatile compounds in a sample, typically with low nanogram sensitivity. Application examples for various juice samples, milk, beer, syrup and sport beverage will be discussed.

    Methods General Considerations for Pulsed Amperometric Detection The Thermo Scientific Dionex UltiMate 3000 LC system with PAD platform consisted of a base-compatible HPLC system, a Thermo UltiMate 3000 ECD-3000RS electrochemical detector and a gold working electrode. Carbohydrates were separated using ion exchange and determined under basic conditions using a four-pulse waveform. It is essential to make sure no titanium is in the flow path as its degradation under basic conditions can lead to deterioration of column and electrode performance. To prevent carbonate formation, all mobile phase should be kept under helium spurge or blanketed under helium gas. Carbohydrate Analysis by HPLC-PAD System:

    Mobile phase: 80 mM sodium hydroxide Flow rate: 1.5 mL/min Injection olume: 25 L Sample preparation:

    Cola soda: 1:1000 dilution in DI water Fruit juice: 1:1000 dilution in DI water, for juice with pulp, centrifuge and filter with 0.2 m filter before dilution Syrup: 100 g/mL dillution in DI water

    Column: Thermo Scientific™ Accucore™ 150-Amide-HILIC, 2.1 x 150 mm, 2.6 m

    Mobile phase: 6% 250 mM ammonium formate, 87% acetonitrile, 7% DI water Flow rate: 0.8mL/min Temperature: 75°C Inj. volume: 3 L Detector: Thermo Scientific™ Dionex™ Corona™ Veo™ SD (evaporator

    temperature high) Sample Preparation:

    Centrifuge with 0.2 m centrifuge filter at 13,000 rpm, 1:100 dilution in DI water, then 1:10 dilution in acetonitrile

    Results and Discussion

    FIGURE 1. Separation of seven common simple food carbohydrates with HPLC-PAD

    Carbohydrates are weak acids, and they are ionized when high pH mobile phase conditions are used. This allows for their separation by anion exchange chromatography, followed by sensitive and direct detection using pulsed amperometric detection. PAD is much more sensitive than UV and refractive index and its sensitivity is comparable to fluorescence detection. It is a very selective and specific detection mode since interferences from sample matrix become invisible to the detector, making sample preparation for many applications as simple as diluting the matrix with deionized water. The reproducibility of detection is enhanced by using a four pulse waveform that keeps the electrode surface clean even when complex samples are injected on the HPLC column. A rapid method for separation of seven simple carbohydrates commonly found in foods and beverages is shown in Figure 1. Simple sugars were completely separated with good resolution within 12 minutes. Figure 2 shows application of this method to fruit juice and soda samples. Several different types of syrup samples are shown in Figure 3 demonstrating the versatility of this HPLC-PAD method. All samples were simply diluted in DI water prior to injection.

    Direct Carbohydrate Analysis with HPLC-PAD

    FIGURE 2. Carbohydrate analysis in fruit juice and cola soda with HPLC-PAD

    FIGURE 4. Lactose and lactulose analysis in milk with HPLC-PAD

    Figure 5 shows a gradient HPLC-PAD method for profiling carbohydrates in beer. This method uses sodium acetate in addition to sodium hydroxide to increase the mobile phase strength to reduce the retention of oligosaccharides. This method allows for separation of malto-oligosaccharides up to DP13-15, as well as separation of some DP≤3 simple sugars such as glucose, fructose, sucrose and maltose, which enables carbohydrate profiling of different types of beer. Three different beers were analyzed, including a double chocolate stout, a Guinness extra stout, and a wheat beer and their carbohydrate profiles are compared in Figure 5.

    FIGURE 5. Carbohydrate profiling for beer with HPLC-PAD method.

    FIGURE 6. Analysis of carbohydrates in various fruit juice sampleswith HPLC- CAD using a Amide-HILIC column.

    FIGURE 7. Carbohydrate and electrolyte analysis of a sports beverage with HPLC-CAD.

    Conclusions

    • Both HPLC-PAD and HPLC-CAD provide simple, direct methods for carbohydrate analysis without the need for sample derivatization. Three HPLC-PAD methods using ion-exchange chromatography for carbohydrate analysis in fruit juice, soda, syrups and milk, as well as an gradient HPLC-PAD method for beer carbohydrate profiling were discussed. Two HPLC-CAD methods using HILIC chromatography are also discussed for carbohydrate analysis in fruit juice and a sports beverage.

    • Pulsed amperometric detection is highly sensitive and selective. Sample preparation can be as simple as dilution in water.

    • Electrochemical detection in DC mode can be used for other food components such as antioxidants, vitamins and amino acids.

    • Charged aerosol detector is a universal mass sensitive detector, and can be used for measurement of any nonvolatile and many semi-volatile analytes. Charged aerosol detection is applicable to many food. This includes antioxidants, amino acids, lipids, proteins, peptides, surfactants, artificial sweeteners, dyes, preservatives and emulsifiers.

    All trademarks are the property of Thermo Fisher Scientific and its subsidiaries. This information is not intended to encourage use of these products in any manners that might infringe the intellectual property rights of others. PO71524-EN 0315S

    Pump: ISO-3100 SD or LPG-3400SD Autosampler: WPS-3000TSL Analytical Autosampler Column: Anion exchange, 4.1 x 250 mm, 7m Temperature: 30 °C EC detector: EC-3000RS with 6041RS sensor and gold target EC Parameters: E1 +200 mV 500 ms AD 300 ms

    E2 -2000 mV 10 ms E3 +600 mV 10 ms E4 -100 mV 10 ms

    HPLC-PAD Method for Simple Sugar Analysis in Fruit Juice, Cola Soda, and Syrup

    HPLC-CAD Method for a Sport Beverage

    HPLC-PAD Method for Lactose and Lactulose Analysis in Milk

    Mobile phase A: 20 mM NaOH Mobile phase B: 200 mM NaOH Flow rate: 1.5 mL/min Gradient: 20 mM NaOH for 20 min, clean the column with 200 mM NaOH at end

    of run for 5 min, then equilibrate with 20 mM NaOH for 10 min Injection volume: 25 L Sample preparation:

    Protein precipitation with 1% perchloric acid at1:10 dilution, centrifuge, then dilute in DI water

    HPLC-PAD Method for Carbohydrate Analysis in Beer

    HPLC-CAD Method for Carbohydrate Analysis in Fruit Juice

    Mobile phase A: 100 mM sodium hydroxide Mobile phase B: 1 M NaOAc in 100 mM NaOH Flow rate: 1.5 mL/min Gradient: 100 mM NaOH for 2 mins, then 100% A to 30% B in 58min,

    gradient curve 6 Injection volume: 20 L Sample preparation:

    1:10 dilution in DI water

    Column: Thermo Scientific™ Acclaim™ Trinity™ P2, 3 x 50mm, 3 m Mobile phase: 20% 100mM ammonium formate at pH 3.65, 80% acetonitrile Flow rate: 0.6 mL/min Temperature: 50°C Inj. volume: 5 L Detector: Corona Veo RS, evaporator 55 °C Sample Preparation:

    Decolorize with Thermo Scientific™ Dionex™ OnGuard™ II P cartridge, dilute 1:40 in mobile phase

    FIGURE 3. Carbohydrate analysis in syrups with HPLC-PAD

    The global prevalence of lactose intolerance has created a large market for lactose-free products and the need for a simple, reliable and accurate method for determination of lactose in milk and other dairy products. The level of lactulose, which is formed by isomerization of lactose during the heat treatment of milk, can be used as an indicator to differentiate milk of different pasteurization or sterilization processes. The AOAC enzymatic method for lactose determination is time consuming and needs extensive reagent preparation. Figure 4 shows a simple HPLC-PAD method for determination of lactose and lactulose in milk within 35 minutes cycle time and requires minimal sample preparation.

    Direct Carbohydrate Analysis with HPLC-CAD

    HPLC with charged aerosol detection is another direct method for carbohydrate analysis. HILIC chromatography is utilized for separation of carbohydrates prior to CAD detection. Charged aerosol detection is a universal detection technique. It allows detection of any non-volatile and many semi-volatile samples independent of analyte chemical structure. Figure 6 shows separation of carbohydrates in various fruit juices on an Accucore Amide 150 column. This column provides excellent resolution and speed of separation of the various carbohydrate species when using decreased amounts of water along with elevated column temperatures. This provides the complete analysis of carbohydrates found in various beverages with a run time of only 6 minutes. Other food products such as honey and different corn syrups (data not shown) have also been successfully analyzed using HILIC chromatography methods with CAD detection. These techniques represent good examples of detecting analytes that possess weak or no chromophores using very simple analytical conditions and sample preparation.

    The method for simultaneous analysis of carbohydrates and electrolytes in a sports beverage shown in Figure 7 represents a good example of the universal character of Corona Veo. An Thermo ScientificTM DionexTM AcclaimTM TrinityTM P2 column was used in HILIC mode for separation in this method. Acclaim Trinity P2 columns offer cation-exchange, anion-exchange and HILIC retention mechanisms on the same phase. The ability of Trinity column to separate organic compounds, cations, and anions simultaneously, together with the universal detection of Corona Veo, allows for separation and detection of carbohydrates and the electrolyte chloride and sodium ions in a single run.

    Fruc

    tose

    G

    luco

    se

    Mal

    tose

    Chl

    orid

    e

    Sod

    ium

    Orange juice

    Apple juice

    Prune juice

    Grape juice

    Cola soda

    Standard

    Whole milk

    Fat free milk

    Lactose free milk

    Maple syrup

    Molasses

    Agave nectar

    Standard

    Grape juice

    Orange juice

    Apple juice

    Prune juice

    Double chocolate stout

    Wheat beer

    Guinness extra stout

    Standard

    0.00 1.00 2.00 3.00 4.00 5.00 6.00 -136

    -100

    -50

    0

    50

    74

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    0.1 10.0 20.0 30.0 40.0 50.0 60.0 -873 -750

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    0

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    957

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  • PN71524-EN 09/16S

    Direct Carbohydrate Analysis in Beverages and Foods Using Pulsed Amperometric Detection or Charged Aerosol DetectionQi Zhang, Bruce Bailey, Dave Thomas, Marc Plante, and Ian AcworthThermo Fisher Scientific, 22 Alpha Road, Chelmsford, MA, USA

    Overview Purpose: To develop simple direct methods for carbohydrate analysis in food and beverage without requirement for sample derivatization. Two approaches are discussed for direct analysis of carbohydrates in various food matrices, highperformance liquid chromatography with pulsed amperometric detection (HPLC-PAD) and high performance liquid chromatography with charged aerosol detection (HPLC-CAD).

    Methods: Three HPLC-PAD methods were developed using ion exchangechromatography, including one isocratic method for simple sugar analysis in fruit juice, soda and syrups, one method for lactose and lactulose analysis in milk, and onegradient method for carbohydrate profiling of beer. Two HPLC-CAD methods using HILIC chromatography are also discussed for carbohydrate analysis in fruit juice and a sports beverage.

    Results: These methods enable rapid separation and reliable determination of carbohydrates in various foods and beverages with simple sample preparation and minimal matrix interference.

    IntroductionCarbohydrates are important food components affecting taste and nutrition. The determination of the types and levels of carbohydrates in foods is important for energyevaluation, nutritional labeling, and quality control and for identifying possible product adulteration.

    Separation and detection of carbohydrates can be challenging. Simple carbohydrates are highly polar, uncharged, and as they lack a chromophore cannot be measureddirectly by UV absorbance detectors. HPLC with various detection techniques has been used for carbohydrate analysis, such as IR, mass spectrometry, UV or fluorescence following derivatization. Although methods utilize derivatization improve the chromatographic resolution and detector sensitivity, they can lead to increasedassay variability. This poster presents two approaches for direct carbohydrate analysis, HPLC-PAD and HPLC-CAD, which solve the challenges for separation and detection without requirement for derivatization.

    Thermo Scientific™ Dionex™ UltiMate™ 3000 Electrochemical Detector now with PAD capabilities when coupled with a gold working electrode provides high sensitivity and selectivity for the measurement of carbohydrates in complex food sample matrices. Thermo Scientific™ Dionex™ Corona™ Charged Aerosol Detector is a mass-sensitivedetector that can measure all non-volatile, and many semi-volatile compounds in a sample, typically with low nanogram sensitivity. Application examples for various juice samples, milk, beer, syrup and sport beverage will be discussed.

    MethodsGeneral Considerations for Pulsed Amperometric DetectionThe Thermo Scientific Dionex UltiMate 3000 LC system with PAD platform consisted of a base-compatible HPLC system, a Thermo UltiMate 3000 ECD-3000RS electrochemical detector and a gold working electrode. Carbohydrates were separatedusing ion exchange and determined under basic conditions using a four-pulsewaveform. It is essential to make sure no titanium is in the flow path as its degradation under basic conditions can lead to deterioration of column and electrode performance.

    To prevent carbonate formation, all mobile phase should be kept under helium spurge or blanketed under helium gas.

    Carbohydrate Analysis by HPLC-PAD System:

    Mobile phase: 80 mM sodium hydroxideFlow rate: 1.5 mL/minInjection olume: 25 L Sample preparation:

    Cola soda: 1:1000 dilution in DI waterFruit juice: 1:1000 dilution in DI water, for juice with pulp, centrifuge andfilter with 0.2 m filter before dilutionSyrup: 100 g/mL dillution in DI water

    Column: Thermo Scientific™ Accucore™ 150-Amide-HILIC, 2.1 x 150 mm, 2.6 m

    Mobile phase: 6% 250 mM ammonium formate, 87% acetonitrile, 7% DI waterFlow rate: 0.8mL/minTemperature: 75°CInj. volume: 3 LDetector: Thermo Scientific™ Dionex™ Corona™ Veo™ SD (evaporator

    temperature high) Sample Preparation:

    Centrifuge with 0.2 m centrifuge filter at 13,000 rpm, 1:100 dilution in DI water, then 1:10 dilution in acetonitrile

    Results and Discussion

    FIGURE 1. Separation of seven common simple food carbohydrates with HPLC-PAD

    Carbohydrates are weak acids, and they are ionized when high pH mobile phaseconditions are used. This allows for their separation by anion exchange chromatography, followed by sensitive and direct detection using pulsed amperometric detection. PAD is much more sensitive than UV and refractive index and its sensitivity is comparable to fluorescence detection. It is a very selective and specific detection mode since interferences from sample matrix become invisible to the detector, making samplepreparation for many applications as simple as diluting the matrix with deionized water. The reproducibility of detection is enhanced by using a four pulse waveform that keeps the electrode surface clean even when complex samples are injected on the HPLC column.A rapid method for separation of seven simple carbohydrates commonly found in foods and beverages is shown in Figure 1. Simple sugars were completely separated with good resolution within 12 minutes. Figure 2 shows application of this method to fruit juiceand soda samples. Several different types of syrup samples are shown in Figure 3 demonstrating the versatility of this HPLC-PAD method. All samples were simply dilutedin DI water prior to injection.

    Direct Carbohydrate Analysis with HPLC-PAD

    FIGURE 2. Carbohydrate analysis in fruit juice and cola soda with HPLC-PAD

    FIGURE 4. Lactose and lactulose analysis in milk with HPLC-PAD

    Figure 5 shows a gradient HPLC-PAD method for profiling carbohydrates in beer. This method uses sodium acetate in addition to sodium hydroxide to increase the mobile phase strength to reduce the retention of oligosaccharides. This method allows for separation of malto-oligosaccharides up to DP13-15, as well as separation of some DP≤3 simple sugars such as glucose, fructose, sucrose and maltose, which enablescarbohydrate profiling of different types of beer. Three different beers were analyzed, including a double chocolate stout, a Guinness extra stout, and a wheat beer and their carbohydrate profiles are compared in Figure 5.

    FIGURE 5. Carbohydrate profiling for beer with HPLC-PAD method.

    FIGURE 6. Analysis of carbohydrates in various fruit juice sampleswith HPLC-CAD using a Amide-HILIC column.

    FIGURE 7. Carbohydrate and electrolyte analysis of a sports beverage with HPLC-CAD.

    Conclusions

    • Both HPLC-PAD and HPLC-CAD provide simple, direct methods for carbohydrateanalysis without the need for sample derivatization. Three HPLC-PAD methods usingion-exchange chromatography for carbohydrate analysis in fruit juice, soda, syrupsand milk, as well as an gradient HPLC-PAD method for beer carbohydrate profilingwere discussed. Two HPLC-CAD methods using HILIC chromatography are alsodiscussed for carbohydrate analysis in fruit juice and a sports beverage.

    • Pulsed amperometric detection is highly sensitive and selective. Sample preparationcan be as simple as dilution in water.

    • Electrochemical detection in DC mode can be used for other food components suchas antioxidants, vitamins and amino acids.

    • Charged aerosol detector is a universal mass sensitive detector, and can be used formeasurement of any nonvolatile and many semi-volatile analytes. Charged aerosoldetection is applicable to many food. This includes antioxidants, amino acids, lipids,proteins, peptides, surfactants, artificial sweeteners, dyes, preservatives andemulsifiers.

    All trademarks are the property of Thermo Fisher Scientific and its subsidiaries. This information is not intended to encourage use of these products in any manners that might infringe the intellectual property rights of others. PO71524-EN 0315S

    Pump: ISO-3100 SD or LPG-3400SDAutosampler: WPS-3000TSL Analytical AutosamplerColumn: Anion exchange, 4.1 x 250 mm, 7mTemperature: 30 °CEC detector: EC-3000RS with 6041RS sensor and gold target EC Parameters: E1 +200 mV 500 ms AD 300 ms

    E2 -2000 mV 10 msE3 +600 mV 10 msE4 -100 mV 10 ms

    HPLC-PAD Method for Simple Sugar Analysis in Fruit Juice, Cola Soda, and Syrup

    HPLC-CAD Method for a Sport Beverage

    HPLC-PAD Method for Lactose and Lactulose Analysis in Milk

    Mobile phase A: 20 mM NaOHMobile phase B: 200 mM NaOHFlow rate: 1.5 mL/minGradient: 20 mM NaOH for 20 min, clean the column with 200 mM NaOH at end

    of run for 5 min, then equilibrate with 20 mM NaOH for 10 minInjection volume: 25 L Sample preparation:

    Protein precipitation with 1% perchloric acid at1:10 dilution, centrifuge, then dilute in DI water

    HPLC-PAD Method for Carbohydrate Analysis in Beer

    HPLC-CAD Method for Carbohydrate Analysis in Fruit Juice

    Mobile phase A: 100 mM sodium hydroxideMobile phase B: 1 M NaOAc in 100 mM NaOHFlow rate: 1.5 mL/minGradient: 100 mM NaOH for 2 mins, then 100% A to 30% B in 58min,

    gradient curve 6Injection volume: 20 L Sample preparation:

    1:10 dilution in DI water

    Column: Thermo Scientific™ Acclaim™ Trinity™ P2, 3 x 50mm, 3 mMobile phase: 20% 100mM ammonium formate at pH 3.65, 80% acetonitrileFlow rate: 0.6 mL/minTemperature: 50°CInj. volume: 5 LDetector: Corona Veo RS, evaporator 55 °CSample Preparation:

    Decolorize with Thermo Scientific™ Dionex™ OnGuard™ II P cartridge, dilute 1:40 in mobile phase

    FIGURE 3. Carbohydrate analysis in syrups with HPLC-PAD

    The global prevalence of lactose intolerance has created a large market for lactose-free products and the need for a simple, reliable and accurate method for determination of lactose in milk and other dairy products. The level of lactulose, which is formed byisomerization of lactose during the heat treatment of milk, can be used as an indicator to differentiate milk of different pasteurization or sterilization processes. The AOAC enzymatic method for lactose determination is time consuming and needs extensive reagent preparation. Figure 4 shows a simple HPLC-PAD method for determination of lactose and lactulose in milk within 35 minutes cycle time and requires minimal sample preparation.

    Direct Carbohydrate Analysis with HPLC-CAD

    HPLC with charged aerosol detection is another direct method for carbohydrate analysis. HILIC chromatography is utilized for separation of carbohydrates prior to CAD detection. Charged aerosol detection is a universal detection technique. It allows detection of any non-volatile and many semi-volatile samples independent of analytechemical structure. Figure 6 shows separation of carbohydrates in various fruit juices on an AccucoreAmide 150 column. This column provides excellent resolution and speed of separation of thevarious carbohydrate species when using decreased amounts of water along with elevated column temperatures. This provides the complete analysis of carbohydrates found in various beverages with a run time of only 6 minutes. Other food products suchas honey and different corn syrups (data not shown) have also been successfullyanalyzed using HILIC chromatography methods with CAD detection. These techniquesrepresent good examples of detecting analytes that possess weak or no chromophoresusing very simple analytical conditions and sample preparation.

    The method for simultaneous analysis of carbohydrates and electrolytes in a sports beverage shown in Figure 7 represents a good example of the universal character of Corona Veo. An Thermo ScientificTM DionexTM AcclaimTM TrinityTM P2 column was usedin HILIC mode for separation in this method. Acclaim Trinity P2 columns offer cation-exchange, anion-exchange and HILIC retention mechanisms on the same phase. The ability of Trinity column to separate organic compounds, cations, and anionssimultaneously, together with the universal detection of Corona Veo, allows for separation and detection of carbohydrates and the electrolyte chloride and sodium ionsin a single run.

    Fruc

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    Standard

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    Fat free milk

    Lactose free milk

    Maple syrup

    Molasses

    Agave nectar

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    Double chocolate stout

    Wheat beer

    Guinness extra stout

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