title: Simultaneous gas chromatographic determination of chlorpyrifos and its impurity sulfotep in liquid pesticide formulations.
abstract: An analytical method for simultaneous determination of the active substance (chlorpyrifos) and its relevant impurity (sulfotep) in commercial pesticide formulations has been developed and validated. The proposed method entails extraction of the analytes from samples by sonication with acetone and analysis by gas chromatography-flame ionization detection (GC-FID). The proposed method was characterized by satisfactory accuracy and precision. The repeatability expressed as relative standard deviation (RSD) was lower than the acceptable values calculated from the modified Horwitz equation whereas individual recoveries were in the range of 98-102% and 80-120% for chlorpyrifos and sulfotep, respectively. The limit of quantification (LOQ) for the impurity (sulfotep) was 0.003 mg mL(-1) corresponding to the maximum permitted level according to Food and Agricultural Organization of the United Nations (FAO) specifications for the active substance (chlorpyrifos) being 3 g kg(-1) of the chlorpyrifos content found. The main advantage of the proposed method was a considerable reduction in the analysis time since both analytes were determined based on a single injection into the GC-FID. Analysis of real samples of commercial pesticide formulations confirmed fitness-for-purpose of the proposed method.
authors.affiliation: a Institute of Plant Protection-National Research Institute Sośnicowice Branch, Pesticide Quality Testing Laboratory , Sośnicowice , Poland.
authors.forename: Marlena
authors.initials: M
authors.lastname: Płonka
authors.affiliation: b Department of Pesticide Residue Research , Institute of Plant Protection - National Research Institute , Poznań , Poland.
authors.forename: Stanisław
authors.initials: S
authors.lastname: Walorczyk
authors.affiliation: a Institute of Plant Protection-National Research Institute Sośnicowice Branch, Pesticide Quality Testing Laboratory , Sośnicowice , Poland.
authors.forename: Marek
authors.initials: M
authors.lastname: Miszczyk
authors.affiliation: a Institute of Plant Protection-National Research Institute Sośnicowice Branch, Pesticide Quality Testing Laboratory , Sośnicowice , Poland.
authors.forename: Dorota
authors.initials: D
authors.lastname: Kronenbach-Dylong
mesh_terms: D004390:Chlorpyrifos / Q000032:analysis*; D002849:Chromatography, Gas / Q000379:methods; D004784:Environmental Monitoring; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D009946:Organothiophosphorus Compounds / Q000032:analysis*; D010573:Pesticide Residues / Q000032:analysis*; D010575:Pesticides / Q000032:analysis*; D015203:Reproducibility of Results
chemical_list: D009946:Organothiophosphorus Compounds; D010573:Pesticide Residues; D010575:Pesticides; D004390:Chlorpyrifos
keywords: Active substance; chlorpyrifos; gas chromatography; impurity; pesticide formulations; plant protection product; sulfotep