Current Issue : October - December Volume : 2019 Issue Number : 4 Articles : 6 Articles
This is the first report describing an analytical method for quantitative analysis of\ntwo naturally occurring sulphur compounds, S-methyl-l-cysteine (SMC) and S-methyl-l-cysteine\nsulfoxide (SMCSO), in human body fluids using isotope-labelled internal standards and liquid\nchromatography-mass spectrometry (LC-MS)/MS techniques. This method was validated according\nto the guideline of the Royal Society of Chemistry Analytical Methods Committee. It offers significant\nadvantages including simple and fast preparation of human biological samples. The limits of detection\nof SMC were 0.08 microM for urine and 0.04 microM for plasma. The limits of detection of SMCSO were\n0.03 microM for urine and 0.02 microM for plasma. The calibration curves of all matrices showed linearity\nwith correlation coefficients r2 > 0.9987. The intra and inter day precisions in three levels of known\nconcentrations were >10% and >20%, respectively................................
A simple, apid, and reliable method based on dispersive solid-phase extraction (d-SPE) and gas chromatography-mass\nspectrometry (GC-MS) was developed for quantitating polychlorinated biphenyls (PCBs) in vegetable samples. Parameters\naffecting both the extraction yields and cleanup efficiency, including the type and volume of extraction solvent, extraction time,\ntype and volume of cleanup sorbent, and cleanup time, were optimized. Matrix effects were evaluated, and matrix-matched\ncalibration was recommended. Under the optimized conditions, carboxylated multiwalled carbon nanotubes (MWCNTs-COOH),\nwhich exhibit excellent adsorption capabilities due to large surface area and unique structure, were employed as d-SPE sorbent to\nremove interfering substances, rather than the analytes, from vegetable samples. Satisfactory linear relationship was observed for\nall PCBs across a concentration range of 5-500 microg/kg with correlation coefficients no less than 0.9993. Four representative\nvegetables (cucumber, tomato, lettuce, and cabbage) were selected as matrices for method validation. Each matrix was spiked at\nconcentrations of 5, 10, and 100 microg/kg to evaluate recoveries, which ranged from 84.5% to 116.5% with relative standard deviations\n(n =6) between 0.6% and 17.6%. /e limits of detection and the limits of quantification ranged from 0.3 to 1.4 microg/kg and 0.8 to\n4.5 microg/kg, respectively. Twelve real vegetable samples were analyzed using the proposed method. /ree of the target PCBs were\ndetected in one lettuce sample with the total concentration of 17.9 microm/kg....
The retention behavior of a wide variety of stationary phases was compared in supercritical\nfluid chromatography (SFC) and normal-phase high-performance liquid chromatography (NP-HPLC).\nWe also attempted to elucidate the retention behavior in SFC by investigating the selectivity of the\ndifferent stationary phases. SFC separation conditions with polar stationary phases, such as silica gel\n(SL) and diol (Diol) phases, operate via adsorptions that include hydrophilic and ionic interactions\nsimilar to those in NP-HPLC. Moreover, non-polar stationary phases, such as pentabromophenyl\n(PBr), pyrenylethyl (PYE), and octadecyl (C18), could be used despite the non-polar mobile phase\nconditions, because the dispersion�������.....
Lead and chromium contamination represents one of the most serious problems in the aquatic environments. 'e aim of this\nwork was to develop and validate an accurate, sensitivity, and rapid method for the simultaneous determination of Pb and Cr at\ntrace levels in tissues and fat of marine organisms such as turtle (Chelonia mydas), shark (Rhizoprionodon terraenovae), and\ndolphin (Tursiops truncatus), utilizing the total reflection X-Ray fluorescence (TXRF) spectroscopy. Working solutions were\nprepared in 10mL of a solution..............................................
Solasodine is a major bioactive ingredient in Solanum nigrum L. that has strong\npharmacological characteristics. Therefore, the development of a simple and effective extraction\nmethod for obtaining solasodine is highly important. This study aims to provide a rapid and eective\nmethod for extracting solasodine from Solanum nigrum L. by microwave-assisted aqueous two-phase\nextraction (MAATPE). Methods: First, the high-performance liquid chromatography (HPLC)\nconditions were established for the detection of solasodine. Then, the aqueous two-phase system\n(ATPS) compositions were examined.Onthe basis of the results of single-factor experiments, for a better\nyield, response surface methodology (RSM) was used to optimize influential factors including the\nextraction temperature, extraction time and liquid-to-solid ratio..............................
A simple and rapid analytical UHPLC methodology with spectrophotometric (UV/Vis)\ndetection, coupled with different extraction procedures, has been perfected to investigate the presence\nof biologically active O-prenylated umbelliferone derivatives, such as auraptene and umbelliprenin,\nin pomegranate (Punica granatum L.) seed extracts. Absolute ethanol was the most efficient extraction\nsolvent in terms of yields, after a short ultrasound-assisted. The highest concentration values recorded\nunder these experimental conditions were 1.99 microg/g of dry extract and 6.53 microg/g for auraptene and\numbelliprenin, respectively. The parent metabolite umbelliferone was also detected (0.67 microg/g). The\nextraction and UHPLC analytical methodology set up in the present study proved to be an efficient,\npowerful, and versatile technique for the simultaneous qualitative analysis and quantification of\noxyprenylated coumarins in pomegranate seed extracts. The characterization of such secondary\nmetabolites in the mentioned phytopreparation represents, to the best of our knowledge, the first\nexample in the literature....
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