Ultrasound-assisted dispersive liquid-liquid microextraction combined withion mobility spectrometery for the determination of chlorpyrifos

Chlorpyrifos is an organophosphorus pesticides (OPPs) extensively applied to improve thequality and quantity of agriculture product owing to their high efficiency relatively and lowpersistence in the environment. However, the consumedly use of OPPs could generate seriouscontamination to the environment, and endanger human health due to the inhibition of theacetylcholinesterase activity in the nervous system. Therefore, it is very important to develop afast, simple, sensitive and reliable analytical method for monitoring of OPPs residues in varioussamples including food, environmental and biological matrixes. In this work an ultrasoundassisteddispersive liquid-liquid microextraction method (US-DLLME) was developed for theextraction and preconcentration of chlorpyrifos prior to its determination by ion mobilityspectrometry (IMS). The laboratory factor affecting the extraction efficiency such as pH, typeand volume of extraction solvent, ultrasound time, centrifuge time, ionic strength and volume ofaqueous phase were examined and optimized. Under the optimum conditions, the calibrationcurve was linear in the range of ۱۵ – ۳۵۰ μg L-۱ (R۲ = ۰.۹۹۹۵). Limit of detection (LOD) based on ۳Sb/m (where m is the slope of calibration graph and Sb is the standard deviation of blank solution) was obtained ۵ μg L-۱. The developed US-DLLME procedure was successfully employed for the determination of chlorpyrifos in tap water and well water samples. The accuracy of the proposed method was examined through the relative recovery determination by spiking the real samples with two levels of chlorpyrifos. The results of this analysis showed that the calculated recoveries were obtained from ۹۴ to ۱۰۱.۷%.