Solid-phase microextraction-based sol–gel technique for the microextraction of Malathion by gas chromatography-mass spectrometry (SPME/GC-MS) method

Pesticides are routinely used in integrated farm management programs to reduce possible losses due to pests. The presence of high levels of pesticides in the food supply may have human health implications and has increased the attention and need to control these organic pollutants. For this reason, monitoring programs have been implemented for determination of these chemicals in foods[1]. a method for applicability of the solid phase microextraction(SPME) procedure for determination of trace amounts of the organophosphorus pesticide malathion from rice as a real sample by gas chromatography (GC) with flame ionization detection (GC-FID) and mass spectrometry (GC-MS) was developed. GO abounds with many oxygen-containing chemical groups across the basal planes, such as epoxy groups, hydroxyl groups, and carboxyl groups, which indicates that it can be readily interacted with other materials [2].GO is more practical than graphene as an adsorbent material and also the porous structure of the sol gel coating offers a high surface area; allowing high extraction efficiency[3]. The influence of various experimental variables such as pH, amount of adsorbent, volume of aqueous and organic solvents, time adsorption and desorption and effect of salt was considered in SPME procedure for the maximum microextraction of malathion.Despite of conventional method for optimization, at this work a limited number of experiments (26 steps) were applied in a cost-effective manner for optimization of 7 variables. A Placket-Burman design was used to evaluate the main factors for the SPME extraction procedure. Thereafter, a central composite design was applied to find out the best optimization conditions. The method presented a linear range from 0.05 to 0.5 ng/mL, LOD obtained 3.89× 10-3 ng/mL and the intraday precision were about of 4.68%. Applicability of the method was verified from real sample of rice with acceptable recoveries 88-97%.