title: An enzyme-linked immunosorbent assay for detecting 3-phenoxybenzoic acid in plasma and its application in farmers and consumers.
abstract: The aim of this study was to identify a plasma biomarker of exposure to pyrethroid insecticides. A major metabolite, 3-phenoxybenzoic acid (3-PBA), can be detected in urine but urinary 3-PBA cannot be used to assess the active dose. The 3-PBA-adduct represents a much more persistent class of biomarkers than metabolites excreted into urine, having half lives up to several weeks or months. We developed an enzyme-linked immunosorbent assay (ELISA) for total 3-PBA including adduct formed after alkaline hydrolysis, liquid-liquid extraction (LLE) and solid phase extraction (SPE) of the sample. The developed ELISA had an IC50value of 26.7 ng/mL. The intra- and inter-assay coefficients of variation (%CV) were lower than 5% and were within the optimum condition variance (OCV) range. The LLE cleanup technique satisfactorily eliminated the matrix effect from plasma samples before SPE and ELISA analysis yielding good recoveries (85.9-99.4%) with a limit of quantitation (LOQ, 5 ng/mL) that was 30- to 47-fold more sensitive than previous studies. Moreover, the developed method could separate more than 80% of 3-PBA from adduct form. The method was successfully applied to the detection of the target in real samples obtained from consumers (n=50) and farmers (n=50). To our knowledge, this is the first ELISA method for detecting 3-PBA in human plasma and applied to a field study.
authors.affiliation: Environmental Science Ph.D. Program, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand ; Research Institute for Health Sciences, Chiang Mai University, Chiang Mai 50200, Thailand.
authors.forename: Sarunya
authors.initials: S
authors.lastname: Thiphom
authors.forename: Tippawan
authors.initials: T
authors.lastname: Prapamontol
authors.forename: Somporn
authors.initials: S
authors.lastname: Chantara
authors.forename: Ampica
authors.initials: A
authors.lastname: Mangklabruks
authors.forename: Chaisuree
authors.initials: C
authors.lastname: Suphavilai
authors.forename: Ki Chang
authors.initials: KC
authors.lastname: Ahn
authors.forename: Shirley J
authors.initials: SJ
authors.lastname: Gee
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Hammock
keywords: 3-phenoxybenzoic acid; Consumer; Enzyme-linked immunosorbent assay; Farmer; Plasma; Pyrethroid insecticides