title: Determination of semi-volatile organochlorine compounds in the atmosphere of Singapore using accelerated solvent extraction.
abstract: Accelerated solvent extraction (ASE) has been applied to the quantitative extraction of organochlorine compounds (OCs), including organochlorine pesticides (HCHs, DDXs) and polychlorinated biphenyls (PCBs) present in both atmospheric particulate and gaseous phase. Extraction parameters such as the combination of solvents, extraction temperature, and static extraction time were investigated and optimized. Effective extraction can be carried out using a 3:1 mixture of n-hexane and acetone as extraction solvents at 100 degrees C in 20min for all the compounds studied. The entire analytical procedure developed in this study proves to be reliable as evident from the analysis of specific surrogate standards with the mean recoveries per sample being greater than 82%. The optimized method was validated using NIST-certified SRM 1649a. Semi-volatile OCs, in the atmosphere of Singapore were quantified using the optimized ASE method together with GC-MS. Total average concentrations of SigmaHCHs, SigmaDDXs, and SigmaPCBs in air samples were 244.9+/-88.5pgm(-3), 7.7+/-4.1pgm(-3), and 34.1+/-19.7pgm(-3), respectively. The distribution of these compounds between the gas and particulate phase is discussed. Possible sources of atmospheric OCs are evaluated based on the molecular ratio of specific compounds and backward air trajectory analysis.
authors.affiliation: Division of Environmental Science and Engineering, National University of Singapore, Engineering Drive 4, Singapore 117576, Singapore.
authors.forename: Jun
authors.initials: J
authors.lastname: He
authors.affiliation: Division of Environmental Science and Engineering, National University of Singapore, Engineering Drive 4, Singapore 117576, Singapore. Electronic address: eserbala@nus.edu.sg.
authors.forename: Rajasekhar
authors.initials: R
authors.lastname: Balasubramanian
authors.affiliation: Division of Environmental Science and Engineering, National University of Singapore, Engineering Drive 4, Singapore 117576, Singapore.
authors.forename: Sathrugnan
authors.initials: S
authors.lastname: Karthikeyan
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, Engineering Drive 4, Singapore 117576, Singapore.
authors.forename: Umid Man
authors.initials: UM
authors.lastname: Joshi
mesh_terms: D000393:Air Pollutants / Q000032:analysis* / Q000302:isolation & purification; D001272:Atmosphere / Q000032:analysis*; D005591:Chemical Fractionation; D008401:Gas Chromatography-Mass Spectrometry; D006843:Hydrocarbons, Chlorinated / Q000032:analysis* / Q000302:isolation & purification; D052638:Particulate Matter / Q000032:analysis; D010573:Pesticide Residues / Q000032:analysis / Q000302:isolation & purification; D011078:Polychlorinated Biphenyls / Q000032:analysis / Q000302:isolation & purification; D012015:Reference Standards; D012846:Singapore; D012997:Solvents / Q000737:chemistry*; D013997:Time Factors; D014835:Volatilization
chemical_list: D000393:Air Pollutants; D006843:Hydrocarbons, Chlorinated; D052638:Particulate Matter; D010573:Pesticide Residues; D012997:Solvents; D011078:Polychlorinated Biphenyls