Application of Dispersive Liquid-Liquid Microextraction for the Analysis of Organophosphorus Pesticides in Hawthorn (Crataegus pinnatifida var. major) Juice Samples

Dispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography equipped with flame photometric detection (GC-FPD) is introduced to extract and determine the fifteen organophosphorus pesticides (OPPs) in hawthorn (Crataegus pinnatifida var. major) juice samples. Some parameters affecting the DLLME efficiency, such as the type and volume of extraction and dispersive solvents, extraction time, and salt concentration, were studied and optimized. The optimized extraction and dispersive solvents are trichloroethane and acetonitrile, respectively. Good linearity was ranged from 0.5 to 100 ng mL(-1) with correlation coefficients from 0.9991 to 0.9999. The limits of quantification (LOQs) varied from 0.15 to 0.3 ng mL(-1), and the limits of detections (LODs) ranged from 0.05 to 0.1 ng mL(-1). The relative standard deviations (RSDs) varied from 1.0% to 2.8% (n = 6) with the relative recoveries in the range of 85.6-119.1%. The method was successfully applied in the determination of OPPs in ten commercial hawthorn juice samples. The chlorpyrifos was detected in one sample.