title: Gas-phase postderivatization following solid-phase microextraction for determining acidic herbicides in water.
abstract: This study analyzes acidic herbicides from an aqueous sample by developing a methylated postderivatization on the fiber following solid-phase microextration (SPME) with diazomethane gas procedure combined with GC/MS. Analysis results indicate that a silica fiber coated with polyacrylate (PA) yields a higher extraction efficiency than that obtained with poly(dimethylsiloxane) (PDMS) using the SPME technique. Detection limits are achieved at the level of 10-30 ng/L. Linearity is obtained over a wide range, with precision below 12% RSD. In addition, the significant reduction in extraction efficiency is attributed to the concentration of humic acids exceeding 5 mg/L. Various degradation compounds of acidic herbicides in basic solution are also detected, including 2,4-dichlorophenol, 2,4,5-trichlorophenol, 4-chloro-3-methylphenol, pentachlorinated biphenyl, and tetrachlorinated biphenyl. Moreover, the amount of pentachlorinated biphenyl and tetrachlorinated biphenyl increases over time.
authors.affiliation: Department of Chemistry, National Chung-Hsing University, Taichung, Taiwan, R.O.C. mrlee@mail.nchu.edu.tw
authors.forename: M R
authors.initials: MR
authors.lastname: Lee
authors.forename: R J
authors.initials: RJ
authors.lastname: Lee
authors.forename: Y W
authors.initials: YW
authors.lastname: Lin
authors.forename: C M
authors.initials: CM
authors.lastname: Chen
authors.forename: B H
authors.initials: BH
authors.lastname: Hwang
mesh_terms: D008401:Gas Chromatography-Mass Spectrometry; D006540:Herbicides / Q000032:analysis* / Q000737:chemistry; D007202:Indicators and Reagents; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014881:Water Supply / Q000032:analysis*
chemical_list: D006540:Herbicides; D007202:Indicators and Reagents; D014874:Water Pollutants, Chemical