title: Evaluation of expanded graphite as on-line solid-phase extraction sorbent for high performance liquid chromatographic determination of trace levels of DDTs in water samples.
abstract: Dichlorodiphenyltrichloroethane (DDT) and its metabolites are a typical kind of persistent organic pollutants (POPs). Development of a simple, cost-effective and sensitive methodology to monitor DDTs concentrations in water environment is of particular significance for understanding the fate and behavior of these pollutants. In this paper, a method on the basis of solid-phase extraction (SPE) using expanded graphite (EG) as sorbent coupled on-line with high performance liquid chromatography (HPLC) was developed for the determination of trace levels of p,p'-DDD (2,2-bis(4-chlorophenyl)-1,1-dichloroethane), p,p'-DDT, o,p'-DDT and p,p'-DDE (2,2-bis(4-chlorophenyl)-1,1-dichloroethene) in water. The analytes in water were preconcentrated onto the SPE column packed with expanded graphite, and subsequently eluted with methanol-water (90:10) mixed solvent. HPLC with a photodiode array detector was used for their separation and detection. The developed on-line solid-phase extraction protocol for HPLC permits the current HPLC separation and the next preconcentration proceeded in parallel, and thus allows one determination within 8min. The precision (R.S.D.) for 10 replicate injections of a mixture of 1mugl(-1) of each analyte was 3.2-6.2% for the peak area measurement. The detection limits (S/N=3) for preconcentrating 50ml of sample solution ranged from 10 to 25ngl(-1) at a sample throughput of 7.5samplesh(-1). The enhancement factors were about 700. The method was applied to the determination of trace p,p'-DDD, p,p'-DDT, o,p'-DDT and p,p'-DDE in local lake, river and tap water samples.
authors.affiliation: Research Center for Analytical Sciences, Department of Chemistry, Nankai University, Tianjin 300071, China.
authors.forename: You-Ya
authors.initials: YY
authors.lastname: Zhou
authors.forename: Shan-Wei
authors.initials: SW
authors.lastname: Wang
authors.forename: Ki-Nam
authors.initials: KN
authors.lastname: Kim
authors.forename: Ji-Hui
authors.initials: JH
authors.lastname: Li
authors.forename: Xiu-Ping
authors.initials: XP
authors.lastname: Yan