Determination of residues of malathion and malaoxon in mango varieties ataulfo and tommy atkins produced in chahuites, oaxaca [Determinación de residuos de malatión y malaoxón en mango de las variedades ataulfo y tommy atkins producidos en chahuites, oaxaca]

The organophosphate pesticide malathion and its metabolite malaoxon cause harmful effects on the health of humans that consume foods contaminated with these molecules. The presence of residues of malathion and malaoxon was studied in mangos (Mangifera indica) of the varieties Ataulfo and Tommy Atkins produced in the municipality of Chahuites, state of Oaxaca, during the harvest period of 2007. The extraction system used ethyl acetate in aqueous matrix, and analytic determination by means of liquid gas chromatography with thermionic specific detector (TSD). The concentration of residues of malathion and malaoxon was determined for each variety through sampling at 1, 30 and 60 d after having applied malathion (520 g i. a. of malathion ha-1), in compliance with the phytosanitary norm (NOM-023-FITO) for the control of the Mexican fruit fly (Anastrepha ludens) on days 1 (T1) and 30 (T2), and two applications of malathion for day 60 (T3). Control mangos of both varieties were used, taken from orchards free of pesticide application for 10 years. The presence of malathion was detected in 75 % and 95.6 % of the samples (n=12) of the varieties Ataulfo and Tommy Atkins. Residues of the metabolite malaoxon were detected in 83.3 % of the samples (n=12) in both varieties. No degradation was observed of either pesticide once it was present in the fruit until day 60 of the study. Furthermore, the means of the residues increased in time three of the study (T3) in both varieties, after two applications of malathion