A reversed-phase high-performance liquid chromatographic (HPLC) method for the selective determination of piperine, in pepper or its oleoresins, is described and evaluated. It employs a fully-capped, bonded CIH stationary phase (ODs-2) and an acetonitrile -aqueous acetic acid mobile phase, with ultraviolet (UV) detection. Piperine is extracted from ground pepper by refluxing 3 h with ethanol (96% v/v), whilst homogenized oleoresins are simply dissolved in the same solvent. At all stages, light must as far as possible be excluded from the solutions, so as to minimize the photoisomerization of piperine. Quantitation, based on peak areas, is achieved by reference to purified piperine as external standard. Results obtained for a range of samples at four different detection wavelengths showed virtual wavelength-independence, indicating a good degree of peak purity. All samples were also analysed by the I S 0 spectrophotometric method (IS0 5564, 1982), which invariably yielded higher results because of the contributions from other pepper alkaloids (e.g. piperyline and piperettine) to the UV absorption. Since some of these other alkaloids are believed to contribute to the pungency of pepper, the HPLC method is proposed as complementary to the spectrophotometric method, rather than as a replacement for it. The HPLC method gave results with relative standard deviations less than +3% for black or white pepper, and piperine values between 75.8% and 90.9% of those yielded by spectrophotometry. Given suitable standards, its use could perhaps be extended to cover the quantitation of other pepper alkaloids, two of whose peaks were tentatively identified. Limited experiments on the use of a synthetic capsaicinoid as an internal standard for piperine determination gave encouraging results, and suggested that piperine might be determined satisfactorily with this means of standardization used in conjunction with an automatic injection system, provided that light could be adequately excluded from solutions awaiting injection.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.