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Residue analysis of chlorpyrifos (an organophosphate pesticide) was investigated in different water samples. Analysis was carried out in collaboration with pesticide residue laboratory Kala Shah Kaku due to the availability of latest chromatographic techniques. Chlorpyrifos was analyzed in different samples of water collected from different sites of Lahore. Sample preparation was done by using Solid Phase Extraction (SPE) technique. Analysis was carried out using High Performance Liquid Chromatography (HPLC). Acetonitrile, methanol solvents were used as mobile phase to achieve the best separation. Chlorpyrifos was detected in 0.161 mg/L-1.912mg/L concentration ranges. Maximum residue limit of chlorpyrifos in drinking water established by either World Health Organization (WHO) or European Union (EU) is 0.040mg/L. The highest concentration of chlorpyrifos residue was 1.912mg/L in water sample collected from Kala Shah Kaku. Study of residue analysis of chlorpyrifos in water has the significant role to solve the environmental problems related to pesticides.

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