Abstract

This research is a continuation of a study on the extraction of organophosphorus insecticides from water using solid phase extraction column loaded with granulated activated carbon. In this study, a wavelength of 220nm was used to monitor its disappearance from water. Prior to extractions processes, the half-life of 0.032, 0.30 and 0.031 hours of monocrotophos was determined in pH6,7 and 8 respectively. The target analyte was extracted from well characterized stream water collected from the middle belt region of Nigeria, distilled water and deionized distilled water using a packed SPE column and eluted with n-hexane. The eluant was analysed using uv-visible spectrophotometer and the percentage recovery of spiked samples were found out to be 68.69%, 85.68% and 80.73% respectively. The percentage recovery from SPE system were compared with recoveries from liquid –liquid extraction method with a percentage recovery from stream water, distilled water and deionized distilled water were 74.50%, 97.54% and 93.65% respectively. Subsequently, the second order rate constant for the extraction of monocrotophos in pH 6,7 and 8 were calculated to have values of 6.0x10-3, 6.42x10-2 and 6.4x10-3 m-1s-1 respectively. The SPE system has a great potential for the removal of organophosphorus insecticides from water.