A rapid, specific and sensitive multi-residue method based on the quick, east, cheap, effective, rugged and safe (QuEChERS) has been developed and validated for the determination of 19 multi-class insecticide and fungicide residues (Aldrin, Amitraz, Bromopropylate, Chlorpyrifos, DDT, Diazinon, Dichlorovos, Ethion, Fenpropathrin, Fenvalerate, Iprodion, Malathion, Metalaxyl, Oxydemethon methyl, Permethrin, Phosalone, Pirimicarb, Profenofos and Tetradifon) in greenhouse cucumber and tomato. Gas chromatography-mass spectrometric detection in selected ion monitoring mode (GC/MS-SIM) was applied for determination of pesticides residues. Quantification was performed using matrix-matched calibration and solvent calibration. Recovery studies were used for comparison of accuracy of each calibration method. Results showed matrix matched calibration would be efficient for quantification of pesticide residues in Iranian cucumber and tomato.

MoSi2-TiC nanocomposite powders were successfully synthesized with different ball to powder weight ratios (BPR) by ball milling of Mo, Si, Ti and graphite elemental powders. Formation of this composite was studied by X-ray diffraction (XRD). Morphology and microstructure of the milled powders were monitored by scanning and transmission electron microscopy (SEM and TEM), respectively. There was incomplete formation in BPR 5:1 after 30 hours of milling, however, the formation of this composite was completed after 10 hours in BPRs 15:1 and 20:1. Higher BPRs with longer milling time led to partially transformation of β to α MoSi2. Based on Rietveld refinement analysis, and subsequent verification by TEM image, nanostructure powders with the mean grain size less than 25 nm were obtained in all BPRs. Very fine submicron powders in agglomerated ones for BPRs 10:1 and 15:1were obtained at the end of milling.