Estudo de método para determinação de resíduos de agrotóxicos em uva por GC-MS

Abstract

The regulatory agencies are becoming increasingly stringent as regards the quality of the food. Thus, the development of analytical methods that help monitoring of pesticide residues, and it is essential in routine laboratories. This study aimed at the development and validation of an analytical method for sample preparation and determination of multiclass pesticide residues in grape variety Isabel. The sample preparation was based on the QuEChERS procedure with determination by gas chromatography coupled to mass spectrometry. Several sorbent materials were tested in the cleaning step of the sample preparation, such as PSA, C18, Florisil, alumina and active carbon, with the sorbent with the highest efficiency in cleaning the extract was the Florisil. The method was defined as follows: 10 g of the sample, peel, pulp and seeds, processed in a blender was added 10 mL of acetonitrile with 1% acetic acid, 4 g of magnesium sulfate and 1 g of sodium acetate. This mixture was stirred manually for 1 minute, centrifuged at 3,000 rpm for 20 minutes. 2 mL of the supernatant was collected and mixed with 300 mg of magnesium sulfate and 400 mg of florisil, which were agitated and centrifuged again. 1 mL of the supernatant was pipetted and brought to a concentrator and the volume reduced to 200l. The efficiency of the method was proven through validation, with detection limits below the maximum residue limits allowed by regulators and recoveries between 70 and 120% with RSD lower than 20% for most pesticides studied, except for trifloxystrobin, tebuconazole and tetradifon. Using the technique matrix matched is extremely important, since it was observed that there was a large positive influence on the performance of the array analysis by increasing the signal chromatographic all analytes studied.