Malathion determination in Rice samples with Graphene oxide reinforced hollow fiber-solid phase microextraction by GC-MASS

A method for applicability of the solid phase microextraction (SPME) procedure for determination of trace amounts of the organophosphorus pesticide malathion by gas chromatography - mass spectrometry (GC-MS) was developed. Graphene oxide reinforced sol–gel which was placed in hollow fiber (HF-SPME) was used for pre-concentration of malathion. In the present study the Plackett-Burman (PB) factorial design was used as a method for first monitoring of Eight factors that have a significant impact and optimized them in next stage, optimization process of significant factor was carried out using a five-level CCD after screening by PBD. the following conditions were selected for the analytical method of Malathion in real sample: amount of GO (0.01gr), pH of aqueous solution (pH: 3), volume of aqueous solution (10000 µl), volume of organic solvent (250 µl), adsorption time (35 min), desorption time (30 min), stirring rate of solution (1000 rpm) and amount of salt (4%). Calibration curves were plotted using three spiking levels of malathion in the concentration ranges of 0.2–0.4-0.5 ng/mL with correlation coefficients (r 2 ) 0.9914 for analytes. Under the optimized extraction conditions, the method showed good linearity (0.05–0.5 ng/mL), repeatability, low limits of detections (3.9×10 -3 ng/mL) and excellent pre-concentration factors (4000). The optimum conditions which were evaluated then applied for the analysis of malathion in the rice as a real sample