Methodological Approach for the Trend Evaluation of Pesticides in Atmosphere: Preliminary Results

Although the pesticides are widely used in agriculture, they, and in particular the relative residues in foodstuff, waters and atmosphere, make a remarkable social alarm and sanitary problems for the harmful effects (carcinogenic and mutagenic effects) producing on the human health. In fact, their spread in waters and atmosphere can produce undesired effects on various organisms and determine the irrigation or drinkable water contamination. Their emission zones are constituted, essentially, by agricultural locations used for alimentary production. In this communication an analytical approach for evaluating the pesticide trend in atmosphere is reported. In particular, the pesticides involved in this research are dimethoate, carbaryl, phorate, cypermethrin, chloridazon, phenmedipham and fluazifop-p-butyl. The GC analysis was carried out using a gas chromatograph equipped with a PTV injector, a capillary fused silica column (25m × 0.20mm × 0.20μm of stationary phase IF 54) and a nitrogen-phosphorus detector and an electron capture detector. The breakthrough curves were determined (the breakthrough volume was above 250 L) using XAD-2 as adsorbent with a recovery of 98.0% for the dimethoate. Further, the dimethoate desorption efficiency from XAD-2 using methanol was studied: the relative average value is about 97%. Experimental tests about the air sample storage demonstrated no significant differences between the samples kept at room temperature (98.0%) and in freezer (98.5%) after a week. In the analyzed concentration range a linearity response was obtained (r= 0.9995) both in GC-NPD and GC-MS, the limits of detection were 0.001 ng μL in GC-NPD and 0.003 ng μL in GC-MS (SIM), respectively, with a relative standard deviation below 9.5%. This approach has been succefully applied to real sample: the preliminary results report the dimethoate concentration decreasing with the distance from the sampling site but it is still persistent in atmosphere after few days from the irrigation.