Atmospheric concentrations of sulfur dioxide, nitrogen oxides, ammonia, hydrogen chloride, nitric acid, formic and acetic acids in the south of Vietnam measured by the passive sampling method.

A passive sampling method was applied to measure the concentrations of air pollutants, such as sulfur dioxide, nitrogen oxides, ammonia, hydrogen chloride, and nitric, formic and acetic acids, in the ambient air at four test sites in the southern region of Vietnam. The monthly averages and the average concentrations of air pollutants during the period from July 2001 to September 2002 are reported here. The concentrations of air pollutants varied widely, depending on the test sites and the sampling periods.

Simultaneous determination of metabolites of trimethylbenzenes, dimethylbenzylmercapturicacid and dimethylhippuric acid, in human urine by solid-phase extraction followed by liquid chromatography tandem mass spectrometry.

We describe a novel method for the determination of three kinds of dimethylbenzylmercapturic acids (DMM) and six kinds of dimethylhippuric acids (DMH), found in urine as metabolites of trimethylbenzenes, based on liquid chromatography/electrospray ionization tandem mass spectrometry. A solid-phase extraction procedure was used for the extractions of DMM and DMH from a urine sample, and the separation was performed on a reversed-phase C(30) column. The analytes were ionized by electrospray in the positive-ion mode.