Abstract

A solid phase microextraction (SPME) headspace sampling technique has been applied to gas chromatography / mass spectrometery for analysis of malathion and fenitrothion residues in wheat. Solid phase microextraction is an innovative solvent free technology that is fast, economical, simplicity and eco-friendly. The 65 µm polydimethylsiloxan (PDMS) fiber was used for the isolation of target compounds from wheat samples. The obtained recoveries of malathion were 91.1 and 104.12% and for fenitrothion were 98.9 and 101.2% for two fortification levels; 0.1 and 1 mg/kg, respectively. In some samples residues of malathion and fenitrothion showed different level of contamination, and in some samples no residues detected. Also, comparison of results with MRL showed that 4 samples have been residues more than MRL and other samples have been less than it. Finally, the results showed this method is good accuracy, precision and sensitivity for determination of residues of these organophosphorus pesticides in wheat.

Key words: Malathion, fenitrothion, residue, solid phase micro extraction (SPME), HS-SPME.