Optimization of a rapid microwave assisted extraction method for the liquid chromatography-electrospray-tandem mass spectrometry determination of isoflavonoid aglycones in soybeans.
ABSTRACT A very fast chromatographic separation of isoflavonoids genistein, daidzein, formononetin and biochanin A was developed on a C18 high-speed column under isocratic conditions. The method was validated in terms of detection limits, quantitation limits (LOQs), linearity and precision. LOQs in 0.04-0.2 microg/g range were calculated, making feasible the determination of these compounds of nutritional concern at trace levels. Good linearity was demonstrated over three concentration orders of magnitude for each analyte (r2 0.990-1.000). The intra-day and inter-day repeatability was evaluated in terms of relative standard deviation (RSD%) at two concentration levels for each analyte (RSD% <9%). An optimization strategy was adopted to find the best conditions for the extraction of isoflavonoid aglycones from yellow soybeans using microwave-assisted extraction. The most relevant parameters resulted to be the microwave power, the extraction time and the acid concentration, optimal values being 600 W, 1 min and 12 M, respectively. When performing sample treatment on a fortified soybean sample, high recovery percentage was obtained for both compounds (94+/-8% for daidzein and 97+/-5% (n = 4) for genistein). The concentration level at which daidzein and genistein were found in the soybean sample were 1.21+/-0.15 mg/g and 2.38+/-0.09 mg/g (n=4), respectively.
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ABSTRACT: A simple and rapid method based on microwave-assisted extraction (MAE) followed by capillary electrophoresis (CE) was developed for the quantification of eight isoquinoline alkaloids in Chelidonium majus L. (Ch. majus). The key parameters affecting CE separation and MAE extraction were investigated and optimized. Complete separation of eight alkaloids was achieved within only 9min using a 500mM Tris-H(3)PO(4) buffer (pH 2.5) containing 50% (v/v) methanol and 2mM HP-β-cyclodextrin. The optimal MAE extraction was performed at 60°C for 5min with methanol-water-HCl (90:10:0.5, v/v/v) as the extracting solvent, which gave much higher extraction efficiency in significantly shorter time than conventional heat reflux extraction (HRE) and ultrasonic extraction (USE) methods. Good linearities were obtained for all the alkaloids investigated with correlation coefficients above 0.9994. The repeatability and intermediate precision were less than 4.11% and the recoveries ranged from 98.0% to 103.9%. The developed method was successfully applied to 14 Ch. majus samples obtained from different regions of China. Compared with previously reported methods, the present method offers a dramatic savings in overall analysis time and considerable reduction in solvent consumption.Talanta 09/2012; 99:932-8. · 3.50 Impact Factor
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ABSTRACT: Genistein (GEN) has potential advantages for topical skin delivery, but no literature data is available for its quantitation in different skin layers, such as the stratum corneum (SC). Therefore, a simple, rapid, selective and sensitive bioanalytical method was developed and validated for GEN quantitation in porcine skin samples following in vitro permeation studies. GEN was assayed by HPLC with UV-vis detection (270<4>nm) using 0.5% acetic acid in water / n-propanol / acetonitrile (50:2:48 v/v/v) as mobile phase (flow-rate of 1.0<4>mL/min). Specificity was demonstrated since endogenous skin components did not interfere with GEN peak. Standard analytical curve was linear over the concentration range (0.1 - 60 µg/mL) and the lower limit of quantitation was determined for different skin layers (100<4>ng/mL). GEN recovery from skin layers ranged from 95.57 to 97.57%. Permeation studies were carried out using an automated vertical diffusion cell apparatus. No fluctuation on the amount of GEN retained in the SC was observed over time, but increasing amounts of the drug were found in deeper layers of the skin. The method was reliable and reproducible for the quantitation GEN in skin samples enabling the determination of the cutaneous penetration profile of this drug in permeation experiments.Biological & Pharmaceutical Bulletin 08/2012; · 1.85 Impact Factor
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ABSTRACT: Most protocols of sample preparation for isoflavone determination in soymilk and other liquid soybean products involves tedious freeze drying and time-consuming extraction procedures. We report a facile and rapid magnetic solid phase extraction (MSPE) of isoflavones from soymilk for subsequent HPLC-ESI-MS/MS analysis. The extraction was based on the selective binding of isoflavones to baicalin functionalized core-shell magnetic nanoparticles (BMNPs). The proposed MSPE-HPLC-MS/MS analytical method had a linear calibration curve in the concentration range from 0.3 to 80 mg/L isoflavones. With the use of calycosin, an isomer of one of the isoflavones targeted as internal standard, inter-day (5 days) precisions of the slope and intercept of the calibration curves were found to be in the range between 2.5% and 3.6% (RSD, n = 5). Six isoflavones, i.e. daidzein, glycitein, genistein, daidzin, glycitin, and genistin were detected in commercial soymilk samples and quantified by the proposed analytical method. The results indicated that the method was useful for fast determination of isoflavones in soymilk and other liquid soybean products.Journal of Agricultural and Food Chemistry 07/2013; · 2.91 Impact Factor