nmr spectroscopy in education - acd/labs. · pdf fileandré j. simpson environmental nmr...

Andr J. Simpson Environmental NMR Centre,
Department of Chemistry, University of Toronto, Canada
NMR Spectroscopy in Education : Using NMR Prediction for Investigation of Red Bull
and The great NMR trivia challenge !

Section 1 : The use of ACD/NMR Predictors in undergraduate education Analysis of RedBull Energy Drink - Mixture Analysis - 1D and 2D prediction and interpretation - DOSY - Limits of Detection and Quantification - Standard Addition Section 2 : The great NMR trivia challenge ! Guess the spectra from a combination of NMR, trivia and advertising slogans.
Summary

Using RedBull to Introduce NMR Spectroscopy
3rd Year Chemistry Lab ~ 40 students year Week 1 Identification (covered here) Week 2 Quantification (not covered) Environmental Science Masters Program ~36-40 student per year
Simpson A. J., Shirzadi, A., Dicks A. P., Burrow T, Lefebvre B. and Corrin T, Use of NMR and NMR prediction software to identify components in red bull energy drinks, J. Chemical Education, 2009, 86, 360-362.

RedBull : Water Suppression
9 8 7 6 5 4 3 2 1 ppm
Simple Presaturation
Receiver Gain = 1
Receiver Gain ~ 32
Simpson A. J., Shirzadi, A., Dicks A. P., Burrow T, Lefebvre B. and Corrin T, Use of NMR and NMR prediction software to identify components in red bull energy drinks, Journal of Chemical Education, 2009, 86, 360-362.

2.83.03.23.43.63.84.04.24.44.64.85.05.25.4 ppm
Expand the central region with the large peaks What is Everything ?
Residual Water

Water, Sucrose, Glucose, Sodium Citric Acid, Taurine
Looking at the Ingredients
Regular Red Bull Sugar Free Red Bull
Start with the sugars

2.83.03.23.43.63.84.04.24.44.64.85.05.25.4 ppm
Sucrose Prediction (Generic Solvent)
Redbull
Sucrose
[5.42]
[4.22][3.58]
O
O[3.77]
O
[4.06]
[3.49]
[3.91]
[3.82]
[3.58; 3.78]
OHOH
OH
OH
OH
[3.73; 3.93]
[3.71; 3.91]
OH
OH
OH
Anomeric Proton

2.83.03.23.43.63.84.04.24.44.64.85.05.25.4 ppm
Glucose Prediction (Generic Solvent)
Redbull
Glucose
Anomeric Proton
O
OH
H[3.41]
H[4.11]
H[3.40]
OH
OH
H[3.80]
OH
H[5.06]
[3.82; 3.83]OH
? ?

2.83.03.23.43.63.84.04.24.44.64.85.05.25.4 ppm
Redbull
What have we learnt ?
For each hexose containing sugar there is an anomeric signal. Anomeric Signals are doublets. NMR shows three types of sugar The RedBull Can only shows two ? (sucrose and glucose)
What is going on ?
3 Anomeric Protons

Isomers !
-glucose -glucose
O
OHH[3.41]
H[4.11]
H[3.40]
OHOH
H[3.80]
OH
H[5.06]
[3.82; 3.83]OH
O
H[4.68]
H[3.24]
H[4.11]
H[3.42]
OHOH
H[3.54]
OH
OH
[3.82; 3.82]OH
[5.43]
[4.33][3.54]
O
O[4.09]
O
[4.22]
[3.39]
[4.03]
[3.88]
[3.75; 3.77]
OHOH
OH
OH
OH
[3.84; 3.84]
[3.91; 3.91]
OH
OH
OH
sucrose
2.83.03.23.43.63.84.04.24.44.64.85.05.25.4 ppm
-glucose
-glucose sucrose
Shift

How can we 100% sure as to assignments
2.83.03.23.43.63.84.04.24.44.64.85.05.25.4 ppm
This is -glucose
This is -glucose If this is Sucrose
1) As a rule -protons generally resonant higher than protons in simple sugars
2) Therefore if we can confirm which anomeric is from sucrose, we will be able to assign the other two
2.83.03.23.43.63.84.04.24.44.64.85.05.25.4 ppm
This is -glucose
This is -glucose If this is
Sucrose

Diffusion Ordered Spectroscopy (DOSY)

Sugars are Identified Next Ingredient Citric Acid
Let the students loose, this one is simple !!! [2.56; 2.74][2.56; 2.74]
O
OOOH
OH
OH OH
Students understand Splitting Pattern and Peak Shape are critically important !

Stepping it Up : Taurine : Dealing With Overlap
Not clear Need more spectral dispersion Move to 1H-13C NMR
S[3.06]
O
O
OH
NH2[3.25]
Fake Scenario ; Athlete loose his gold medal if he doped with Taurine Can the students identify and quantify Taurine ?

1H-13C HMQC Red Bull
Mixture Prediction
2D ACD/NMR Predictors are very useful: 1) Confirm all the assignments thus far AND clearly identify Taurine. 2) Students to learn that the patterns rather that the exact chemical shifts are important for assignment.

ppm
2.62.83.03.23.43.63.84.04.24.44.64.85.05.2 ppm
40
50
60
70
80
90
100
Now Taurine is assigned can the 1D be used for quantification ? 99% of the students say yes

TAURINE
Much Larger Sugar Signals
Students forget about spectral overlap. Oblique View Shows how the Taurine signals are swamped.

Caffeine in the Aromatic Region
7.27.37.47.57.67.77.87.98.08.18.28.38.48.58.68.78.88.9 ppm
Generic Solvent Predictions Lack of Splitting Pattern Need Representative Predictions

Caffeine in the Aromatic Region
7.27.37.47.57.67.77.87.98.08.18.28.38.48.58.68.78.88.9 ppm
Prediction in Water

Niacin Limits of Detection/Quantification
7.27.37.47.57.67.77.87.98.08.18.28.38.48.58.68.78.88.9 ppm
O
N
OH
S/N ~ 10:1; 8 scans,~30s
S/N ~ 60:1; 256 scans,~16 min
~30ug in coil

2.83.03.23.43.63.84.04.24.44.64.85.05.25.4 ppm
Regular RedBull
Sugar free RedBull
Regular vs. Sugar Free RedBull Sugar Region
S[3.06]
O
O
OH
NH2[3.25]

7.27.37.47.57.67.77.87.98.08.18.28.38.48.58.68.78.88.99.0 ppm
Regular RedBull
Sugar free RedBull NH
OOO
CH3
NH2
OH
O
Aspartame
Aromatic Region

0.850.900.951.001.051.101.15 ppm
The Big Finish - Flavorings ?
Alanine Mystery ?

0.850.900.951.001.051.101.15 ppm
The Big Finish - Flavorings ?
Alanine
COSY, HMBC CH3-CH2-XH ?
Simpson A. J., Shirzadi, A., Dicks A. P., Burrow T, Lefebvre B. and Corrin T, Use of NMR and NMR prediction software to identify components i

nmr spectroscopy in education - acd/labs. · pdf fileandré j. simpson environmental nmr...

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