Organophosphorus pesticides determination by novel HPLC and spectrophotometric method

The present work describes a novel HPLC and UV-spectrophotometric method for the simultaneous estimation of chlorpyrifos and prophenofos in vegetables and fruits. In UV method, the absorbance of chlorpyrifos and prophenofos was measured at wavelength 277nm and 289nm respectively and quantitation was carried out by first order derivative method. The calibration curve for chlorpyriphos and prophenofos was found to be linear in the range of 6-16μg/mL with correlation coefficient 0.9979 and 0.9993 respectively. The HPLC separation was achieved on Hibar C₁₈ column (250×4.6mm, 5µ) using mobile phase consist of acetonitrile: water (90:10, v/v) at flow rate 1.0mL/min and the eluent was monitored at 219nm. Pesticides were extracted from the samples by solid phase extraction and liquid-liquid extraction before the analysis. Out of these two extraction methods, solid phase extraction was found more efficient in terms of % recovery as compared to liquid-liquid extraction. The developed method was applied for estimation of chlorpyrifos and prophenofos and it was found that the chlorpyrifos was 0.018mg/kg, which is above maximum residue limits (0.01mg/kg), which might be toxic to body. Prophenofos was not found in any collected samples of vegetables and fruits.