title: Comparative evaluation of ELISA kit and HPLC DAD for the determination of chlorpyrifos ethyl residues in water and sediments.
abstract: Enzyme linked immunosorbent assay (ELISA) kit is a versatile, cheap and relatively available tool that can be used in remote areas. In this study, performance of ELISA kit was evaluated in terms of accuracy, recovery, precision, sensitivity, cross reactivity and matrix interference for pesticide residue determination in water and sediment samples. This method was compared with high performance liquid chromatography (HPLC) which is not a commonly available analytical technique for chlorpyrifos ethyl residue analysis in developing countries. The ELISA kit had limits of detection (LOD) of 0.37 µg L(-1) and 0.42 µg Kg(-1) dry weight (dw), for chlorpyrifos ethyl in water and sediment samples, respectively using deionized water and a control sediment sample. Mean percentage recoveries and coefficients of variation (CV) for ELISA kit varied from 96.0±5.8% to 108.0±3.4% for water and sediment samples. Comparison between ELISA and HPLC analysis results using water and sediment samples from Lake Naivasha showed no significant difference in results (p≤0.05). Strong correlations (r2=0.9878 water samples and r1=0.9670, p<0.0001 for sediment samples, n=48) were reported between the methods for the two samples analyzed. Bland-Altman bias plot analysis showed that the two methods were in agreement within 95% confidence interval of limits -2.9 to 3.8 and -2.2 to 3.6 for water and sediment, respectively. Given the high sensitivity reported and the obtained acceptable limits of coefficient of variation and percentage recovery, ELISA appears to be a suitable rapid analytical tool in analysis of chlorpyrifos ethyl in water and sediment samples. Results demonstrate comparability to HPLC and could complement conventional tools in regular monitoring program particularly in developing countries. This will hasten results delivery for ecological risk assessment and timely execution of mitigation measures.
authors.affiliation: Department of Chemistry, Maseno University, P.O. Box 333, 40105 Maseno, Kenya; Helmholtz Center Munich - German Research Center for Environmental Health (GmbH) Molecular EXposomics (MEX), Ingolstädter Landstreet 1, D-85764 Neuherberg, Germany. Electronic address: tudor20082000@yahoo.com.
authors.forename: P O
authors.initials: PO
authors.lastname: Otieno
authors.forename: P O
authors.initials: PO
authors.lastname: Owuor
authors.forename: J O
authors.initials: JO
authors.lastname: Lalah
authors.forename: G
authors.initials: G
authors.lastname: Pfister
authors.forename: K-W
authors.initials: KW
authors.lastname: Schramm
mesh_terms: D004390:Chlorpyrifos / Q000031:analogs & derivatives / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods / Q000592:standards*; D019015:Geologic Sediments / Q000737:chemistry*; D006801:Humans; D007630:Kenya; D060106:Lakes / Q000737:chemistry*; D057230:Limit of Detection; D010573:Pesticide Residues / Q000032:analysis*; D015203:Reproducibility of Results; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D010573:Pesticide Residues; D014874:Water Pollutants, Chemical; D004390:Chlorpyrifos
keywords: Chlorpyrifos ethyl; ELISA; HPLC; Sediment; Validation; Water quality