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HomeThin Layer ChromatographyDetermination of Quinine in Tonic Water and Caffeine in Coffee and Cola Drinks Using TLC-MS

Determination of Quinine in Tonic Water and Caffeine in Coffee and Cola Drinks Using TLC-MS

Section Overview

Abstract

High-Performance Thin Layer Chromatography coupled with Mass spectrometry (HPTLC–MS) is an analytical technique that requires low-level of sample preparation. Here it is illustrated with the determination of quinine in tonic water and caffeine in coffee and cola drinks. Tonic water and the analyzed cola drinks were decarbonized through ultrasonication, and boiled coffee was extracted through an appropriate 0.45 µm PTFE syringe filter. After the initial chromatographic separation, specific bands were eluted with an TLC-MS interface and detected with mass spectrometry.

Results

Caffeine (hRf = 56, m/z = 195.2, 236.2, Figure. 2) and quinine (hRf = 37, m/z = 325.4, Figure. 4) were detected under UV light (254 nm, Figure. 1; 366nm, Figure. 3) and measured by TLC-MS.

Slide and graph of developed plate at 254 nm and mass spectrum of caffeine in coffee.

Figure 1.(left) Developed plate at 254 nm. Figure 2. (right) Mass spectrum of caffeine in coffee.

Slide and graph of developed plate at 366 nm and mass spectrum of quinine in tonic water.

Figure 3. (left) Developed plate at 366 nm; Figure 4. (right) mass spectrum of quinine in tonic water

Conclusion

These results demonstrate that caffeine and quinine can easily be analyzed by HPTLC-MS with a minimum of sample preparation in coffee, cola drinks or tonic water.

TrackCompoundConc. [mg/mL]Application
volume [µL]
hRfDetected mass m/z
1Caffeine standard1156195.2, 236.2
2Coffee 156195.2, 236.2
3Cola drinks 156195.2, 236.2
4Tonic water 137325.4
5Quinine standard1137325.4
6Caffeine standard1256195.2, 236.2
7Coffee 256195.2, 236.2
8Cola drinks 256195.2, 236.2
9Tonic water 237325.4
10Quinine standard1237325.4
Table 1.Chromatographic data
Chromatography
PlateHPTLC Silica gel 60 F254 MS-grade, 20x10cm
Sample preparationCaffeine and quinine standard diluted in Methanol;
Cola drinks and tonic water were decarbonated; Coffee boiled and filtered with a 0.45 µm syringe filter.
Sample applicationATS 4 sample applicator (Camag), 6 mm bandwise
Application volume1.0 and 2.0 µL
Mobile phaseIsopropanol / n-Heptane / Water 7/3/1 + 1% Triethylamine
Migration distance5 cm
Migration time49 min
Extraction 
Extraction equipmentTLC-MS Interface “Plate Express” (Advion)
Extraction solventAcetonitrile / Water 95/5 (v/v) + 0.1% Formic acid
Extraction flow0.2 mL/min
Detection 
WavelengthUV light at 254 nm and 366 nm
StainingNone
MS equipmentexpression CMS (Advion)
MS detectionESI (+) mode (m/z 150 - 400)
Table 2.Application data
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