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.
Article: CHROMATOGRAPHY: RECENT PROGRESS[show abstract] [hide abstract]
ABSTRACT: In recent years, substantial research has been devoted to the development of new liquid-liquid microextraction methods for sample preparation. These microextration methods were performed by several techniques such as: liquid-phase microextraction (LPME) or membrane-assisted solvent extraction (MASE), hollow fiber liquid phase microextraction (HF-LPME), single drop-phase microextraction (SDME), liquid-liquid-liquid-microextraction (LLLME), dispersive liquid-liquid microextraction (DLLME), and ionic liquid dispersive liquid-liquid microextraction (IL-DLLM). Performance extraction increasing was achieved by using the ultrasound field; techniques such as: ultrasound-asisted liquid phase microextraction (ULPME), ultrasound-asisted ionic liquid dispersive liquid-phase microextraction (UILDLPM), ultrasound-asisted dispersive liquid-liquid microextraction (UDLLME) and ultrasound-asisted headspace liquid-phase microextraction (UHS-LPME) being used for extraction from complex matrix. Also microwave field was used for solid sample preparation emprouving. Other techniques such as solid phase extraction (SPE), solid phase microextraction (SPME) and stir bar solvent extraction (SBSE) were frecventlly used in liquid sample preparation. The best results are obtained after careful optimization.Journal of Liquid Chromatography & Related Technologies - J LIQ CHROMATOGR RELAT TECHNO. 01/2012;
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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
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ABSTRACT: A simple extraction procedure and HPLC method was developed to analyse the major and minor components of induced phytoalexins of elicited tissues (seeds) of chickpeas (Cicer arietinum L.) and peas (Pisum sativum L.) treated with a biotic elicitor (k-carrageenan) of Hypnea musciformis (red algae) from the Karachi coast. The level and timing of the induced phytoalexin production were estimated on the basis of various elicitor dilutions and as a function of time; the results are presented and discussed. A LC-ESI-MS/MS technique has been employed for the detection and characterisation of the induced phytochemical components (flavonoids and their glyco-conjugates). Nine flavonoids were identified from chickpeas: naringin, naringin malonate, liquiritigenin, naringenin, biochanin A, daidzein, formononetin, maackiain and medicarpin, while five flavonoids were identified from peas: afrormosin, anhydropisatin, pisatin, pseudobaptigenin and maackiain. These compounds play a vital role as phytoalexins because of their antimicrobial activity.Natural product research 08/2011; 25(14):1352-60. · 1.01 Impact Factor