analysis of caffeine in coffee kate penrod, nikki deluca, christina robinson, and jess bases
TRANSCRIPT
Analysis of Caffeine in Coffee
Kate Penrod, Nikki DeLuca, Christina Robinson, and Jess Bases
Purpose
• Quantify caffeine in brewed coffee– Varying strengths
• Extract caffeine from grounds
• Maxwell House: Regular and Decaf.
Background
• Caffeine in food/drink• CNS stimulant• Schedule V drug• High levels– Restlessness– Irritability– Headaches– Heart complications
Methods
• HPLC– Liquid
• Separation– Liquid
• IR– Solid and liquid
• SFE – Solid
• UV/Vis– Disabled
HPLC
• Hypothesis• Samples– 10-50ppm caffeine standards– Strong caffeinated/decaffeinated– Regular caffeinated/decaffeinated– Weak caffeinated/decaffeinated
• Dilution of coffee samples
Sample Conc [ppm] Retention Time Area
Standard 10 2.346 1026491
Standard 20 2.323 1360973
Standard 30 2.314 1612710
Standard 40 2.305 1915989
Standard 50 2.302 2330806
Weak DC 1:2 46.55369153 2.266 1436697
Reg DC 1:5 77.88165933 2.293 1193080
Str DC 1:5 227.381635 2.283 2139010
Weak C 1:5 180.6469498 2.294 1843306
Reg C 1:10 321.8074968 2.313 1718385
Str C 1:25 548.2456002 2.310 1394082
Organic Separation• Sample Preparation (Dr. Peterman’s Coffeemaker) – Regular Caffeinated/ Decaffeinated
• 1 Tbsp. grounds, ¾ cup water
– Strong Caffeinated/ Decaffeinated• 3/2 Tbsp. grounds, ¾ cup water
– Weak Caffeinated/ Decaffeinated • ½ Tbsp. grounds, ¾ cup water
Organic Separation• First Method– Adapted from Dr. Halligan’s Organic I Lab Manual– Extraction of Caffeine using
Dichloromethane– Large emulsion layer,
not a clear separation
Organic Separation• Revised Method– Added Na2CO3 which increased
caffeine’s solubility in aqueous layer– Separation layer more pronounced– Dried with Anhydrous MgSO4
– Vacuum under reduced pressure
Mass QuantificationAppearance Mass of Product
Regular Caffeinated Yellow/brown liquid 0.2753g
Weak Caffeinated Light brown liquid 0.2731g
Strong Caffeinated Yellow/ brown solid, black spots
0.2892 g
Regular Decaffeinated Yellow/brown liquid 0.2006 g
Weak Decaffeinated Light brown liquid 0.2001g
Strong Decaffeinated Yellow/ brown liquid 0.2296 g
Extracted Caffeine IR Characterization
Substituted Alkene
Extracted Caffeine IR Characterization
Strong DecaffRegular Decaff
Weak Decaff
C = N
C = O
O – H stretchC = N
C = O
Substituted Alkene
Substituted Alkene
C = O
C = N
O – H stretch
CH3C - N
Substituted Alkene
Extracted Caffeine IR Characterization
Strong Caffeinated Regular Caffeinated
C = O
C = N
O – H stretch
CH3C - N
Substituted Alkene
C = O
C = N
O – H stretch
CH3
C - N
Substituted Alkene
Substituted Alkene
C - NCH3
C = NO – H stretch
Weak Caffeinated
The Devil’s Instrument a.k.a. SFE
The Devil’s Instrument a.k.a. SFE
• 4 Samples– “Pure” coffee grounds– Post brewing coffee grounds
• 1 gram of each sample• 10 minute runs• End mass indications• IR results
SFE DataSample Percent Yield
Pure Caffeinated 5.186 %
Pure Decaf. 6.286 %
Brewed Caffeinated 1.185 %
Brewed Decaf. 3.576 %
UV/Vis
• Attempted to use the DRA-600– Solid Analysis
• Missing part!• Call EVERYONE– Manufacturer– Distributor– Delivery Guy
• Piece was backordered until May 20th
• Put on hold INDEFINITELY.
Sources of Error
• Organic Method– Impure caffeine for mass quanitification– Transfer between different glassware– Incomplete drying in extraction (O-H stretch peak)
• HPLC– Day 1: Low pressure, purge lines– Day 2: Invalid date/time error, inconsistent– Day 3: Consistent results, ran all samples
Sources of Error (Part 2)
• SFE– Leaks in the line– Issues with the amount of sample– Needed constant supervision
• UV/Vis– Missing part– Phone tag– Wasted 2 whole lab periods
Sources of Error (Part 3)
Jerry Sainsbury – Sales RepresentativeThermo Fisher Scientific
Conclusions• HPLC:
• Strong decaf. was comparable to weak caf.• Weak and regular brews – 4:1 caf. vs. decaf.• Strong brew – 5:2 caf. vs. decaf.
• Organic Method:• Qualitative data• Erroneous quantitative data• Masses very similar
• SFE:• Low percent yields• Higher yield from decaf
• Did not extract pure caffeine• May be caffeine plus side products
• If UV/Vis hadn’t been in the initial method, further research would have been conducted
Further Research
• Organic Method– Develop a new or revised method to extract pure
caffeine in its solid form as was done in Dr. Halligan’s Organic I Lab
• IR– Analyze liquid only– Create calibration curve
• HPLC– Compare different coffee makers and brands
Further Research (Part 2)
• SFE– Brew remaining grounds, analyze with HPLC– Determine other components of extracted
grounds• UV/Vis– Obtain calibration disc and sample holder– Develop SOP for DRA-600