Method for determination of stable carbon isotope ratio of methylnitrophenols in atmospheric particulate matter

摘要

A technique for the measurement of the stable isotoperatio of methylnitrophenols in atmospheric particulate matter is presented.Atmospheric samples from rural and suburban areas were collected forevaluation of the procedure. Particulate matter was collected on quartzfibre filters using dichotomous high volume air samplers. Methylnitrophenolswere extracted from the filters using acetonitrile. The sample was thenpurified using a combination of high-performance liquid chromatography andsolid phase extraction. The final solution was then divided into twoaliquots. To one aliquot, a derivatising agent,Bis(trimethylsilyl)trifluoroacetamide, was added for Gas Chromatography-MassSpectrometry analysis. The second half of the sample was stored in arefrigerator. For samples with concentrations exceeding 1 ng μl−1, thesecond half of the sample was used for measurement of stable carbon isotoperatios by Gas Chromatography-Isotope Ratio Mass Spectrometry.The procedure described in this paper provides a method for the analysis ofmethylnitrophenols in atmospheric particulate matter at concentrations aslow as 0.3 pg m−3 and for stable isotope ratios with an accuracy ofbetter than ±0.5‰ for concentrations exceeding 100 pg m−3.In all atmospheric particulate matter samples analysed,2-methyl-4-nitrophenol was found to be the most abundant methylnitrophenol,with concentrations ranging from the low pg m−3 range in rural areas tomore than 200 pg m−3 in some samples from a suburban location.