Abstract

HERRERO, Florencia; RODRIGUEZ, María Soledad; CANAS, Ana Irene  and  LUCERO, Patricia Antonia. Validation of a method for the determination of 3-phenoxybenzoic acid in urine using QuEChERS, microextraction liquid-liquid dispersive and high-performance liquid chromatography-diode array. Acta toxicol. argent. [online]. 2018, vol.26, n.1, pp.19-31. ISSN 1851-3743.

Pyrethroid insecticides are used not only in the agricultural and domestic environment, but also in public health. Once absorbed, they are rapidly metabolized into polar compounds eliminated by the kidneys. One of the metabolites common to many pyrethroids is 3-phenoxybenzoic acid (3-PBA) which are used to evaluate exposure. We present in this paper the validation of an analytical methodology for the determination of 3-PBA using QuEChERS coupled to dispersive liquid-liquid microextraction with trichloroethylene as an extractive solvent and high-performance liquid chromatography with a photodiode array detector. Validation was carried out with isolated samples of urine from adult volunteers of both sexes without exposure and synthetic urine. The method was linear in the interval 9 μg L^-1-79 μg L^-1; the limit of detection and quantitation were 3 μg L^-1 and 9 μg L^-1, respectively. Interfering signals were not observed in the blank urine samples and the chromatographic signals in the enriched samples were spectrally homogeneous. The within-run precision (RSDr%) (n = 5) for 9 μg L^-1 were between 9.3%-9.9% and for 27 μg L^-1 between 5.9%-10.6%. The between-run precision (RSDint%) (n = 15) for the same concentration levels were 11.8% and 9.1%, respectively. The recovery for 9 μg L^-1 ranged from 87%-119% and for 27 μg L^-1 from 70%-91 %. The stability of the analyte was evaluated in the sample and in the extract. The analyte in the sample was stable at -20 °C for 7 days and in the extract was stable for 1 day. The values of relative uncertainty and expanded uncertainty obtained by the Horwitz equation were 33% and 65% for 9 μg L^-1, and 28% and 55% for 27 μg L^-1. The applicability of the validated method was evaluated with real samples of people without known occupational exposure, who declared having used pyrethroid insecticides. The method was sensitive and selective.

Keywords : Validation; 3-phenoxybenzoic acid; Pyrethroids; Urine.

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