چكيده فارسي :
Pesticides are a diverse group of chemical compounds, which are used to eliminate pests in agriculture. Despite their many merits, pesticides are toxic and environmentally stable substances. Since metalaxyl ,as an agricultural fungicide, has the concern regarding potential human and wildlife exposure from residues and metabolites. Metalaxyl has been found to induce skin irritation, accumulate in the liver, muscles, or fat, and cause tumors of suprarenal thyroid glands [1].Therefore, many analytical methods have been reported to determine metalaxyl. Rezaee el al.[2] developed a novel microextraction technique, termed dispersive liquid-liquid microextraction (DLLME), in which the appropriate mixture of extraction and disperser solvent are injected into an aqueous sample by syringe, resulting in the formation of a cloudy solution, which can markedly increase the contact surface between phases and reduce the extraction time. The use of water-miscible organic dispersive solvents in DLLME could reduce the partition coefficient of analytes with respect to the extraction solvent. To conquer this drawback, some dispersive solvent-free techniques were developed, in which the extraction solvents were dispersed into the aqueous. Farajzadeh and Mogaddam developed a novel simple microextraction technique without dispersive solvent termed as air-agitated liquid – liquid microextraction (AALLM) in which, fine organic droplets are formed by repeated pulling in and pushing out of the mixture of aqueous sample solution and extraction solvent in a conical test tube by means of a syringe [3]. Air-agitated liquid-liquid based on solidification of a floating organic droplet coupled with gas chromatography-mass spectrometry (GC-MS) was developed for determination of metalaxyl. 1-undecanol, with melting point near room temperatur was chosen as extraction solvent which solidiefies after axtraction process to be easily separated from the aqouos solution. Under the optimum conditions, good linearity was observed in a range of 0.05-200 µg L-1 with the correlation coefficient (r2) 0.9930 for analyte. The limit of detection (LOD) was 0.002 µg L-1. The developed method was successfully applied to determine the metalaxyl in cucumber and tomato.
