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Article Title

A gas chromatographic method for determination of nicotinamide, paraben esters and caffeine in commercial health drinks, tonic drinks and cold formulas

Abstract

A simple and rapid method was developed to simultaneously determine the nicotinamide, paraben as well as caffeine by using megapore immediate-polar column (CP-Sil 24CB, 30 m x 0.53 mm, 1.5 μm) with direct injection gas chromatography. Direct quantitative analysis of nicotinamide, paraben esters and caffeine in health drinks, tonic drinks, and cold formulas was carried out without any sample pretreatment procedure. The water soluble compound 1,9-nonanediol was used as an internal standard. The detection limit for nicotinamide, paraben esters and caffeine was 2 μg/mL. Recovery studies were performed using 1 mL of vitamin B drink, tonic drink and cold solution, each spiked with nicotinamide, paraben esters and caffeine at 100.0 μg, respectively. The recoveries for nicotinamide were 96, 102 and 105%, respectively, and the coefficient of variation was less than 7.2%. The recoveries for butylparaben were 105, 95, and 107%, respectively, and the coefficient of variation was less than 8.3%. The recoveries for caffeine were 101, 95 and 104%, respectively, and the coefficient of variation was less than 7.5%. Fifty-two commercial health drinks, tonic drinks and cold solutions were analyzed by the current method. The nicotinamide content was found as: 20.3-241.7, 0-210.7 and 0-246.8 μg/mL, respectively; the isobutylparaben content was found as: 0-54.1, 0-42.9 and 0-134.1 mg/mL; the butylparaben content was found as: 0-106.8, 0-120.1 and 0-184.6 μg/mL; and the caffeine content was found as: 0-433.2, 0-80.7 and 472.3-1742.9 μg/mL. These results indicated that 6 out of 18 commercial health drinks, 2 out of 12 commercial tonic drinks, and 2 out of 22 commercial cold formulas exceeded the Taiwan nicotinamide recommended daily nutrient allowances (RDNA, 14.4 μg) level. Furthermore, 25 out of 52 samples labeled 'preservative-free' were detected to be preservative-containing products. The total preservative contents in some test samples exceeded the regulation levels of 100 μg/mL; and 27 out of 30 samples were detected to be caffeine-containing products. These results were inconsistent with the CNS (Chinese National Standard) rules.

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