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.

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

Figure 3. (left) Developed plate at 366 nm; Figure 4. (right) mass spectrum of quinine in tonic water
Track | Compound | Conc. [mg/mL] | Application volume [µL] | hRf | Detected mass m/z |
---|---|---|---|---|---|
1 | Caffeine standard | 1 | 1 | 56 | 195.2, 236.2 |
2 | Coffee | 1 | 56 | 195.2, 236.2 | |
3 | Cola drinks | 1 | 56 | 195.2, 236.2 | |
4 | Tonic water | 1 | 37 | 325.4 | |
5 | Quinine standard | 1 | 1 | 37 | 325.4 |
6 | Caffeine standard | 1 | 2 | 56 | 195.2, 236.2 |
7 | Coffee | 2 | 56 | 195.2, 236.2 | |
8 | Cola drinks | 2 | 56 | 195.2, 236.2 | |
9 | Tonic water | 2 | 37 | 325.4 | |
10 | Quinine standard | 1 | 2 | 37 | 325.4 |
Chromatography | |
---|---|
Plate | HPTLC Silica gel 60 F254 MS-grade, 20x10cm |
Sample preparation | Caffeine 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 application | ATS 4 sample applicator (Camag), 6 mm bandwise |
Application volume | 1.0 and 2.0 µL |
Mobile phase | Isopropanol / n-Heptane / Water 7/3/1 + 1% Triethylamine |
Migration distance | 5 cm |
Migration time | 49 min |
Extraction | |
Extraction equipment | TLC-MS Interface “Plate Express” (Advion) |
Extraction solvent | Acetonitrile / Water 95/5 (v/v) + 0.1% Formic acid |
Extraction flow | 0.2 mL/min |
Detection | |
Wavelength | UV light at 254 nm and 366 nm |
Staining | None |
MS equipment | expression CMS (Advion) |
MS detection | ESI (+) mode (m/z 150 - 400) |
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