Optimization of dispersive liquid-liquid microextraction procedure for detecting chlorpyrifos in human urine samples

Background: Selecting an effective sample preparation method to measure target pesticides in biological matrices is a serious challenge for researchers. This study aimed to optimize the dispersive liquid-liquid microextraction (DLLME) technique to obtain a simple, valid, and fast method with high efficiency to detect chlorpyrifos in urine samples. Methods: DLLME, coupled with high performance liquid chromatography equipped with ultra violet detector, was used to extract chlorpyrifos pesticide in human urine samples. Different affecting parameters on the efficiency of the method were optimized using one factor at a time method. Results: The limit of detection and enrichment factor of the method was 0.5 and 230 µg L-1, respectively. Linear calibration curve with 1-500 µg L-1 concentration range was used. The relative standard deviation (RSD) for 6 replicate experiments at the concentration of 200 µg L-1 was less than 5%. The relative recoveries of spiked urine samples were 96.3%, 102.3%, and 98.7% at 3 different concentration levels of 50, 200, and 1000 µg L-1, respectively. Conclusion: Compared to other extraction techniques, the optimized DLLME resulted in some advantages such as shorter extraction time, high extraction efficiency, and good enrichment factor for the extraction of chlorpyrifos from human urine samples.