RESUMO
A method was developed for the determination of aflatoxin B1 in medical herbs (senna pods, botanical name Cassia angustifolia; devil's claw, botanical name Harpagophytum procumbens; and ginger roots, botanical name Zingiber officinale). The method, which was tested in a mini-collaborative study by 4 laboratories, is based on an immunoaffinity cleanup followed by reversed-phase high-performance liquid chromatography separation and fluorescence detection after post-column derivatization. It allows the quantitation of aflatoxin B1 at levels lower than 2 ng/g. A second extractant (acetone-water) was tested and compared to the proposed methanol-water extractant. Several post-column derivatization options (electrochemically generated bromine, photochemical reaction, and chemical bromination) as well as different integration modes (height versus area) were also investigated. No differences were found depending on the choice of derivatization system or the signal integration mode used. The method was tested for 3 different matrixes: senna pods, ginger root, and devil's claw. Performance characteristics were established from the results of the study and resulted in HorRat values ranging from 0.12 to 0.75 with mean recoveries from 78 to 91% for the extraction with methanol-water and HorRat values ranging from 0.10-1.03 with mean recoveries from 98 to 103% for the extraction with acetone-water. As a result, the method, with all tested variations, was found to be fit-for-purpose for the determination of aflatoxin B1 in medical herbs at levels of 1 microg/kg and above.
Assuntos
Aflatoxina B1/análise , Aflatoxina B1/isolamento & purificação , Cassia/metabolismo , Técnicas de Química Analítica/métodos , Calibragem , Cromatografia de Afinidade/métodos , Cromatografia Líquida de Alta Pressão/métodos , Metanol/química , Fotoquímica , Reprodutibilidade dos Testes , Espectrometria de FluorescênciaRESUMO
NIR reflection and ATR-IR spectroscopy methods are developed to determine the echinacoside content in roots of Echinacea angustifolia and Echinacea pallida. Based on the recorded spectra and the HPLC reference data, chemometrical analyses are performed using a partial least squares (PLS) algorithm. Generally, good calibration statistics are obtained for the prediction of the echinacoside content presenting comparatively high coefficients of determination (R(2)) and low root mean standard errors of cross validation (RMSECV). It is demonstrated that optimal predictions are possible when using a dispersive spectrometer covering the spectral range from 1,100 to 2,500 nm. In contrast to the time-consuming HPLC method, the described non-destructive measurements allow us to predict the echinacoside content already after an analysis time of approx. one minute. Both spectroscopic techniques presented in this paper are shown to be useful in agricultural practice as well as in the phytopharmaceutical industry.
