a b s t r a c tIn this study, dispersive liquid-liquid microextraction (DLLME) combined with ultra-high-pressure liquid chromatography (UHPLC)-tunable ultraviolet detection (TUV), has been developed for pre-concentration and determination of triclosan (TCS), triclocarban (TCC) and methyl-triclosan (M-TCS) in aqueous samples. The key factors, including the kind and volume of extraction solvent and dispersive solvent, extraction time, salt effect and pH, which probably affect the extraction efficiencies were examined and optimized. Under the optimum conditions, linearity of the method was observed in the range of 0.0500-100 g L −1for TCS, 0.0250-50.0 g L −1 for TCC, and 0.500-100 g L −1 for M-TCS, respectively, with correlation coefficients (r 2 ) > 0.9945. The limits of detection (LODs) ranged from 45.1 to 236 ng L −1 . TCS in domestic waters was detected with the concentration of 2.08 g L −1 . The spiked recoveries of three target compounds in river water, irrigating water, reclaimed water and domestic water samples were achieved in the range of 96.4-121%, 64.3-84.9%, 77.2-115% and 75.5-106%, respectively. As a result, this method can be successfully applied for the rapid and convenient determination of TCS, TCC and M-TCS in real water samples.
Fatty acid synthase (FAS) is a potential target for cancer, but potent inhibitors against FAS are scarce. In this study, we found that activities of catechins on inhibiting FAS increased greatly by heating them in acid. The enhancement was positively correlated to H þ concentration. The inhibitory activities of the final products from different catechins were similar, all of which were less than 1 mg/mL. The product from (2 )-epigallocatechin gallate (EGCG) was stable at room temperature, and its inhibitory kinetics and reacting sites on FAS were obviously different from the known FAS inhibitors. It also affected the viability of MCF-7 cells more obviously than EGCG. A putative route of the reaction progress was proposed and the effective inhibitors were deduced to be oligomers of 2-hydroxy-3-(3 0 , 4 0 , 5 0 -trihydroxyphenyl) propenoic acid by analysis of their spectra. The work affords new and potent FAS inhibitors that would be promising candidates for the treatment of cancer.
A solid phase extraction-high performance liquid chromatography/electrospray ionization-tandem mass spectrometry (SPE-HPLC/ESI-MS/MS) method for the determination of 3 sweeteners (acesulfame (AK), sodium saccharin (SA), sodium cyclamate (SC)) in vinegars has been developed. The sample was diluted with acidic water, then purified and enriched with a weak anion exchange SPE column. The HPLC separation was performed on a Pursuit C18 column (150 mm x 2.0 mm, 3 microm) by gradient elution with 10 mmol/L ammonium acetate containing 0.1% (v/v) ammonia water and acetonitrile as the mobile phases. The analytes were detected by ESI--MS/MS in multiple reaction monitoring (MRM) mode to satisfy qualitative and quantitative detections. Good linearities (r2 > 0.99) were obtained over the range of 0.01 - 0.50 mg/L. The limits of quantification (LOQs) for SA, AK and SC were 10, 5 and 5 microg/kg, respectively. The average recoveries ranged from 72.1% to 96.8% at the spiked levels of 0.01 and 0.1 mg/L with the relative standard deviations (RSDs) less than 15%. This method is accurate, highly sensitive for qualitative and quantitative analysis of the 3 sweeteners in vinegars.
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