RESUMEN
Degradation of parathion methyl on lemon and apple on the trees, during storage of these fruits in refrigerated rooms, and during juice production was studied. The pesticide was applied to the trees according to the recommended application procedures. Apples and lemons received a single application of parathion methyl at 40 g active ingredient/100 litres. Residues were determined with a simple gas-chromatographic method; the recovery rate of parathion methyl from apples and lemons was 85-108% and the limit of determination was 0.004 mg kg(-1). The half-lives of parathion methyl on the trees were 7 days for apples and 5 days for lemons. The duration of storage of the fruits in a refrigerated room have been largely extended to 65 and 63 days, respectively. The high acidity of lemons was found not to affect the degradation rate of parathion methyl. When fruit juice was produced from both apples and lemons, parathion methyl residues were detected in apple but not in lemon juice.
Asunto(s)
Contaminación de Alimentos , Manipulación de Alimentos , Conservación de Alimentos , Frutas , Insecticidas/química , Metil Paratión/química , Citrus , Concentración de Iones de Hidrógeno , MalusRESUMEN
The degradation of azinphos methyl in orange and peach juice was studied. The insecticide was aseptically added to packed orange and peach juices and stored at 40, 20 and 0 degrees C. Samples were removed at regular intervals and were analysed for residues of azinphos methyl. Residues were determined with a simple gas-chromatographic method using a 30 m glass capillary column and an NP detector. The recoveries of azinphos methyl were 87-110% for orange juice and 92-108% for peach juice, and the limit of determination was 0.004 mg/kg for both juices. From the experimental data, rate constants, half-lives, and times needed to reach legal limits for the decomposition of azinphos methyl in orange and peach juices were evaluated. Half lives for orange and peach juices were 6.5 and 7.8 days at 40 degrees C, 86.6, and 92.4 days at 20 degrees C, and 407.7 and 495.1 days at 0 degrees C, respectively.
Asunto(s)
Azinfosmetilo/química , Bebidas/análisis , Residuos de Medicamentos/química , Frutas/química , Insecticidas/química , Temperatura , Cromatografía de Gases , Semivida , Humanos , Concentración de Iones de Hidrógeno , Concentración Máxima Admisible , Factores de TiempoRESUMEN
Decomposition of the pesticide methidathion on and in soultanina (Thomson seedless) grapes was studied. Vines, uncovered and covered were sprayed with the pesticide. Samples were collected and analyzed in regular time intervals. Two lots were collected, the first of them, 2 h after spraying and the second 20 days later, and were stored in a commercial refrigerated room. Degradation of the pesticide was studied for about 50 days for the grapes on the vines and 130 days for the grapes stored in the refrigerated room. The half-life of the pesticide methidathion was found to be 5 days for the uncovered vines, 7 days for the covered vines and 64 days for the grapes stored in the refrigerator.
Asunto(s)
Insecticidas/química , Compuestos Organotiofosforados/química , Residuos de Plaguicidas/análisis , Rosales/química , Cromatografía de Gases , Manipulación de Alimentos , CinéticaRESUMEN
Residue levels of parathion methyl on field-sprayed Granny-Smith apples were studied. The pesticide was applied according to producer recommendations. Apples received a single spraying at a rate of 40 g active ingredient/100 L. Residues were determined with a simple gas chromatographic method. Recovery of parathion methyl was 88-108%, and the limit of determination was 0.002 mg/kg. Decomposition of parathion methyl was studied in apples remaining on trees after spraying and in apples harvested and stored under ambient-temperature, refrigerated-room, and controlled-atmosphere conditions. During post harvest storage, parathion methyl degrades more slowly than on apples remaining on the trees. Best-fit curves were determined, and kinetic equations, rate constants, and half-lives were calculated. Half-lives found were 8 days for apples on trees, 45 days for apples stored at ambient conditions, 68 days for apples stored in controlled-atmosphere room, and 62 days for apples stored in a refrigerated room. Under storage conditions, levels of parathion methyl residues need a long time to become lower than the legal limit (0.2 mg/kg).