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<strong>Clujul</strong> <strong>Medical</strong> 2006 vol. LXXX - nr. 1<br />
Intens.<br />
x104<br />
8<br />
6<br />
4<br />
2<br />
0<br />
3. +MS2(194.9), 2.6-3.0min<br />
194.9<br />
175 180 185 190 195 m/z<br />
Fig. 3. Electrospray positive ion MS spectra for caffeine.<br />
The caffeine content in all samples was determined on the basis of the<br />
calibration curve obtained by applying the proposed method. The standard curve was<br />
prepared over 7 different concentrations in the range 0.26-26 µg/ml for caffeine. Peak<br />
areas were plotted against the corresponding concentrations using a quadratic model<br />
with a 1/Y weighting scheme in order to generate the calibration curve (determination<br />
coefficients are greater than 0.995).<br />
Fig. 4. The calibration curve for<br />
caffeine.<br />
The developed HPLC/MS method was then used for quantification of caffeine<br />
in 7 instant coffee samples and 11 cappuccino samples that are frequently consumed by<br />
Romanian people. The results in Table I show that the concentration of caffeine in the<br />
instant coffee samples is between 3.277 and 4.753 g%, while in the cappuccino samples<br />
the content in caffeine is much smaller, between 0.013 and 0.605 g%. These results are<br />
in accordance with the dose of caffeine estimated for each beverage based on the usual<br />
volume dispensed, which is of 65-100 mg caffeine per serving of instant coffee and of<br />
0,002-0,080 g caffeine per serving of cappuccino 4 .<br />
192
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