Redalyc.Methodological Approach for the Trend Evaluation of Pesticides
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Revista CENIC. Ciencias Químicas ISSN: 1015-8553 [email protected] Centro Nacional de Investigaciones Científicas Cuba Vincenzo Russo, Mario; Avino, Pasquale; Bisignani, Raffaella Methodological Approach for the Trend Evaluation of Pesticides in Atmosphere: Preliminary Results Revista CENIC. Ciencias Químicas, vol. 36, 2005 Centro Nacional de Investigaciones Científicas La Habana, Cuba Disponible en: http://www.redalyc.org/articulo.oa?id=181620511032 Cómo citar el artículo Número completo Sistema de Información Científica Más información del artículo Red de Revistas Científicas de América Latina, el Caribe, España y Portugal Página de la revista en redalyc.org Proyecto académico sin fines de lucro, desarrollado bajo la iniciativa de acceso abierto Revista CENIC Ciencias Químicas, Vol. 36, No. Especial, 2005 Methodological Approach for the Trend Evaluation of Pesticides in Atmosphere: Preliminary Results Mario Vincenzo Russo1*, Pasquale Avino2 and Raffaella Bisignani1 1 Facoltà di Agraria (DISTAAM), Università del Molise, 2 Laboratorio Inquinamento Chimico dell’Aria, Dipartimento Insediamenti Produttivi e Interazione con l’Ambiente – Istituto Superiore per la Prevenzione E la Sicurezza sul Lavoro, Via De Sanctis – 86100 Campobasso (Italy). Ph.: +39-0874-404-634; Fax: +39- 0874-404-652; E-mail: [email protected] Via Urbana 167 – 00184 Rome (Italy). Ph.: +39 064714242, Fax: +39 064744017; E-mail: [email protected] ABSTRACT: 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 (r2= 0.9995) both in GC-NPD and GC-MS, the limits of detection were 0.001 ng µL-1 in GC-NPD and 0.003 ng µL-1 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. Keywords: Pesticides, Atmosphere, GC analysis, Air quality, XAD-2 adsorbent. INTRODUCTION The pesticides are particular chemical substances that have found wide employment in the agricultural sector. Their properties have allowed to obtain high product amount and quality in comparison to the periods in which the pesticides were not employed. The pesticides can be classified on their properties as herbicides, insecticides etc.; furthermore, according to their chemical composition they can be divided in chlorinated pesticides, phosphorousthionate, nitrogenous etc.. In any case, even if they develop very well their action in agricultural field, often their residues have been found in foods, in waters and in air1-11 creating a notable social alarm and sanitary problems for the dangerous effects on humans. In fact, many of them have carcinogenic and mutagenic effects: they have been found consistent residues in different human organ tissues.12 A direct consequence of the continuous and massive use of pesticides is the possibility that a certain amount of these substances can move from the agricultural basins to superficial waters through superficial slide phenomena (runoff) or can reach the soil through infiltration phenomena (leaching) or can disperse themselves in atmosphere through transport and diffusion phenomena reaching inhabited or industrial centers. The diffusion of these pesticides in water and in atmosphere can produce some unwanted effects on not- target organisms and determine the contamination of drinkable and/or irrigation waters. The principal objective of this research is the identification of the presence, the concentration levels and the behavior of pesticides in atmosphere also considering the water and soil environment. Revista CENIC Ciencias Químicas, Vol. 36, No. Especial, 2005 Experimental part Sampling Site The site involved in this research is located in the Molise region (near Campobasso), in the Center of Italy: the location is an agricultural site cultivated at sugar beet. The intensive sampling campaign was performed in springtime. The location is characterized essentially by agricultural activities but there also are a little industrial site, a little town and a creek. Materials and Reagents A personal pump (Zambelli srl, Milan, Italy) was used for air sampling (rate 2 L min-1). Pyrex glass tubes (12 cm × 0.6 mm) were used for packing XAD-2 adsorbent13. For storing the water and soil samples the sterile glass box were employed. All the samples were stored at 4°C and -5°C for seven days and after analyzed using the procedure below reported: in Table 1 are reported the results. Table 1. Dimethoate recovery after 7-day sample storage at 4°C and -5°C. Samples stored at 4°C Day storage Dimethoate added Dimethoate found Recovery (µg) (µg) % 7 97.9 95.7 97.8 7 97.9 95.5 97.6 7 97.9 96.3 98.4 Samples stored at -5°C 7 97.9 96.5 98.5 7 97.9 96.1 98.2 7 97.9 96.7 98.8 7 0.0 0.0 blank Dimethoate, omethoate, mevinfos, dicrotofos, disulfoton, paration methyl, formothion, paraoxon ethyl, fenitrotion, malaoxon, paration ethyl, iodofenfos, triazofos, M20, phosalone, pirazofos e tribulyl phosphate and standards were furnished by Riedel-de Haen (Seelze, Germany). The methylene chloride, acrylonitrile, hexane, acetone, methanol, toluene, sodium sulphate anhydrous and pure reagents for pesticides were furnished by Carlo Erba (Milan). GC and GC-MS analysis The GC analysis has been performed by means a gas chromatograph mod. 86.10 HT (Dani, Monza, Italy) equipped with a PTV (programmed temperature vaporizer) injector, a fused silica capillary column (25 m × 0.20 mm × 0.20 µm of stationary phase SE 54) and nitrogen-phosphorous (NPD) and an Electron Capture (ECD) Detectors. The experimental conditions were: PTV from 60°C to 280°C at 800 °C/min; detector temperature at 290°C; column temperature at 90°C (1 min in isotherm) and after up to the final temperature of 280°C at 10 °C/min. Hydrogen as vector gas at flux of 38 cm/s and nitrogen (UPP) as auxiliary gas, internal standard (IS) M20. For the GC-MS analysis a gas chromatograph mod. 5890 (Hewlett and Packard, Palo Alto, CA, USA) connected to a mass spectrometry mod.5070 (HP) was used. The GC-MS column was a fused silica capillary column (25 m × 0.20 mm × 0.20 µm of stationary phase SE 54). The experimental conditions were: column temperature 90°C (1 min. in isotherm) and after the final temperature of 280°C at 5 °C/min. Helium was used as vector gas at 15 psi; the injector and transfer line temperatures were 270°C and 260°C, respectively. The data was acquired in SCAN and SIM modes. In SIM mode the ion mass was: dimethoate (229; 125 and 87), omethoate (213; 141 and 72) tributylphosphate, internal standard (99; 155 and 266). Sample collection and analysis Before treatment with pesticides air samples were randomly collected along the direction North, South, East and West. During may the site was undergone to pesticide treatment such as copper oxichloride and rogor (dimethoate). The dimethoate amount involved ranged between 0.3-0.7 kg/ha. Two hours after the treatment 12 air samples were collected for 1 h-long at the following distances: a) 4 samples at 100 m far from the point; b) 4 air samples at 200 m; c) 4 air samples at 300 m. Further, at 500, 800 and 1000 m some passive samplers were used at 2 m-height.All the samples were stored at -5°C. Revista CENIC Ciencias Químicas, Vol. 36, No. Especial, 2005 The glass fiber filter and the 270 mg (XAD-2) “sampling section” were transferred into 4 mL-vial and 2 mL of methanol, 5 µL of tributylphosphate (IS) and M20 were added: the solution were mixed for 90 min. The organic phase was recovered, concentrated (200-250 µL) and analyzed by means of GC-NPD and GC-MS in SIM mode (Selected Ion Monitoring). The passive samplers were extracted through CS2 (5 mL × 2) and, after the IS adding, the solution was dried and recovered with 250 µL of methanol. A few µL were used for the GC-NPD and GC-MS analyses. Validation of analysis procedure Evaluation of breakthrough volume and retention efficiency14,15 - 19 µL of a solution 5.15 mg mL-1 dimethoate in toluene were added to each home-prepared glass tube with XAD-2 used for air sampling: they were stored at room temperature overnight. After an air stream was flown through them for volumes such as 50, 100, 150, 200 e 250 L and the glass fiber and the 270 mg XAD-2 were undergone to the same procedure described above.