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A rapid and simple method to determine taurine in energy drinks by pre-column high-performance liquid chromatography was developed using a derivative of 4-fluoro-7-nitrobenzofurazan (NBD-F) without the need for an exclusive instrument. The reaction of taurine with NBD-F finished in 10 min at 60• C. The derivative was measured on a UV-Visible detector (470 nm) by HPLC using a conventional Octadecyl silane (ODS) column. A mixture of disodium hydrogenphosphate-citric acid buffer solution (pH 5.4) containing 10 mmol/l tetrabutylammonium bromide and acetonitrile (7:3) was used as the mobile phase. The recoveries were in the range of 98.2-99.9%, the precision as standard deviation was in the range of 0.3-0.5%, the linearity as a coefficient of correlation value was 0.999 and the specification was confirmed for taurine added to three commercial energy drinks. The content of taurine measured compared to the labeled amount in five commercial energy drinks containing taurine was 92.9-105.1%.

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Simple and rapid analysis of aristolochic acid (AA) in crude drugs and Kampo extracts using a solid-phase extraction method and HPLC-PDA analysis was investigated. Extraction of AA from samples was accomplished by adding methanol containing 1% ammonia. The addition of ammonia ionized the AA of acidic substances so that they adhered to an acrylamide copolymer of a strong anion exchange resin (Sep-Pak QMA) coupled to diol silica easily. Furthermore, a mixture of acetonitrile-water-phosphoric acid (75:25:2, v/v) was effective in isolating AA from its carrier. Since almost all interfering peaks originating from contaminants in crude drugs and Kampo extract formulations could be removed, a satisfactory HPLC chromatogram of AA was obtained. A good result was also obtained when Aristolochiaceae and crude drugs containing AA were tested. Particularly in the case of the medicinal parts of Asarum, several interfering peaks and a ghost peak detected near the AA peak were eliminated. The AA contents of two Kampo extract formulations, tokishigyakukagoshuyushokyoto and ryutanshakanto, were calculated by HPLC analysis. The AA content (the sum of AA-I and AA-II) was 1.25-6.13 mg per daily dose. From an additional recovery experiment for Kampo formulations, high recovery rates of AA were obtained. Neither LC/MS nor special instrumentation was necessary. Our results suggest that this simple, quick, and sensitive analytical method to detect AA in crude drugs and Kampo extract formulations would be valuable in safety inspections of AA in crude drugs and their products.

The sennoside A (SA) and sennoside B (SB) contents of various samples of crude drugs were determined using solid-phase extraction (SPE) and HPLC. The samples examined were crude drugs (senna leaf, senna pods, and rhubarb), conventional crude drug products, and Kampo formulations. The sample solution was purified using an Oasis MAX cartridge, which has strong anion-exchange and reversed-phase properties. The samples containing SA and SB were dissolved in a solution of methanol-0.2% sodium bicarbonate (7:3, v/v) and applied to the Oasis MAX cartridge. The cartridge was washed with a solution of methanol containing 1% acetic acid. SA and SB were eluted with methanol-water-formic acid (70:30:2, v/v), and the eluate was used as the sample solution for HPLC analysis. SA and SB were analyzed using a conventional octadecylsilyl (ODS) column at a detection wavelength of 380 nm; water-acetonitrile-phosphoric acid (800:200:1, v/v) was used as the mobile phase. The SA and SB components in most samples were completely separated from other interfering constituents within 10 min. In particular, several interfering peaks adjacent to the SB peak were eliminated by SPE using the Oasis MAX cartridge. On subjecting the Kampo extracts to an additional recovery experiment, high recovery rates of SA and SB were obtained. The method employed in this study proved to be a simple and rapid method for the quantification of SA and SB.