Jian-Lin Wu

Triclosan determination in water related to wastewater treatment.

Triclosan in the waste, river and sea water samples collected in Hong Kong was analyzed by using gas chromatography-ion trap mass spectrometry method. (13)C(12)-triclosan was used as internal standard for the quantitative analysis. Water samples were prepared and cleaned-up by using a C(18) solid-phase extraction cartridge. The recoveries of triclosan in spiked coastal water at three different concentrations ranged from 83 to 110%. The method detection limit was 0.25 ng/L for triclosan in 1-L water and the relative standard deviations and relative error were less than 11.0 and 12.3%, respectively (n=3). The method was successfully applied to analyze water samples collected from rivers, coastal water bodies and wastewater treatment plants at ng/L levels.

Investigation of levels and fate of triclosan in environmental waters from the analysis of gas chromatography coupled with ion trap mass spectrometry.

A gas chromatography-ion trap mass spectrometry method was developed and optimized for the analysis of triclosan in water. Tandem mass spectrometry, along with an isotope dilution internal standard method, was used for the quantitative analysis of triclosan in water at low ng l(-1) levels. The efficiencies obtained from liquid-liquid extraction and solid-phase extraction were compared. Average recoveries by the SPE pre-concentration using a C(18) cartridge were determined as 84-90%. The limit of detection was 2 ng l(-1) for triclosan in water. The accuracy represented by relative analytical errors was -16% to -10%, and the precision by relative standard deviations was 3-15% (n=4). The method was successfully applied to analyze triclosan at concentrations between 4.1 ng l(-1) and 117 ng l(-1) in environmental water samples collected from rivers and coastal water in Hong Kong.

One single LC-MS/MS analysis for both phenolic components and tanshinones in Radix Salviae Miltiorrihizae and its medicinal products.

A LC-MS/MS method was developed for the separation and simultaneous determination of phenolic components including danshensu, protocatechuic acid, protocatechuic aldehyde and caffeic acid as well as tanshinones including cryptotanshinone, tanshinone I and tanshinone IIA in samples of Radix Salviae Miltiorrhizae and Salviae Miltiorrhizae tablet. Triple quadrupole mass spectrometry was optimized in both positive and negative ion multiple reaction monitoring modes for the simultaneous quantitative analysis of the two different types of active components by using a time-segment program. The method gave recoveries of 85.4-106.4% with relative standard deviations of 2.4-8.0% for the spiked herb samples. The limits of detection were 0.30-0.83mug/g for the analysis of 1.0g Radix Salviae Miltiorrhizae or tablet samples.

Determination of triclosan metabolites by using in‐source fragmentation from high‐performance liquid chromatography/negative atmospheric pressure chemical ionization ion trap mass spectrometry

Triclosan is a widely used broad-spectrum antibacterial agent that acts by specifically inhibiting enoyl-acyl carrier protein reductase. An in vitro metabolic study of triclosan was performed by using Sprague-Dawley (SD) rat liver S9 and microsome, while the in vivo metabolism was investigated on SD rats. Twelve metabolites were identified by using in-source fragmentation from high-performance liquid chromatography/negative atmospheric pressure chemical ionization ion trap mass spectrometry (HPLC/APCI-ITMS) analysis. Compared to electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (MS/MS) that gave little fragmentation for triclosan and its metabolites, the in-source fragmentation under APCI provided intensive fragmentations for the structural identifications. The in vitro metabolic rate of triclosan was quantitatively determined by using HPLC/ESI-ITMS with the monitoring of the selected triclosan molecular ion. The metabolism results indicated that glucuronidation and sulfonation were the major pathways of phase II metabolism and the hydroxylated products were the major phase I metabolites. Moreover, glucose, mercapturic acid and cysteine conjugates of triclosan were also observed in the urine samples of rats orally administrated with triclosan.

High performance liquid chromatography–mass spectrometry analysis for rat metabolism and pharmacokinetic studies of lithospermic acid B from danshen

Metabolism and pharmacokinetic studies on rat were conducted for lithospermic acid B, one of the components from Radix Salviae Miltiorrhizae (danshen) that shows many bioactivities. Liquid chromatography-electrospray ionization mass spectrometry method was applied for the determination of lithospermic acid B and its metabolites in samples from in vitro and in vivo metabolism studies. Rat plasma samples collected after intravenous administration were analyzed for obtaining pharmacokinetic data of lithospermic acid B. Four O-methylated metabolites, namely one monomethyl-, two dimethyl- and one trimethyl-lithospermic acid B, were detected when lithospermic acid B was incubated in rat hepatic cytosol. These four metabolites were also detected in rat bile, plasma and feces samples after intravenous administration of lithospermic acid B. The in vitro and in vivo results indicate that the methylation is the main metabolic pathway of lithospermic acid B. The danshen component and its methylated metabolites were excreted to rat bile and feces.

Determination of amino acids in colon cancer cells by using UHPLC-MS/MS and [U-13C5]-glutamine as the isotope tracer

Rapid and simple quantitative analysis of intracellular metabolites is a critical tool for monitoring the alteration of biologically significant metabolites in cell lines or in vivo. We established an ultra-high performance liquid chromatography (UHPLC) method, equipped with hydrophilic interaction liquid chromatography (HILIC) column coupled to tandem mass spectrometry (MS/MS) for the simultaneous determination of 19 amino acids and 2 related derivatives in human cell lines. Chromatographic separation was achieved within 20min using a BEH amide column, with aqueous mobile phase containing 20mM ammonium acetate and 20mM ammonium hydroxide, and acetonitrile as the organic mobile phase. Amino acids were analyzed in positive ion multiple reaction monitoring (MRM) mode without the need of derivatization. Intra- and inter-day precisions were less than 13.7%. The method was successfully applied to simultaneously detect the 21 compounds in a human colon cancer cell line DLD1. Moreover, metabolite fate of glutamine-derived carbons into amino acids in DLD1 cells was successfully traced by using [U-13C5] glutamine as the isotope tracer. Metabolic consequences of glutaminolysis inhibition on amino acid metabolism were evaluated. Analysis of 12C- and U-13C-labeled amino acids revealed the significantly decreased incorporation of [U-13C5]-glutamine derived carbons into aspartate, alanine and ornithine, indicating impaired metabolic flux via the tricarboxylic acid cycle and the urea cycle.