Determinação simultânea de glifosato, ácido aminometilfosfônico e glufosinato em grãos de café verde por LC-MS/MS: otimização, validação e análise das espécies Coffea arabica e Coffea canephora

Abstract

Coffee is one of the most important commodities for Brazil, which ranks as the world's largest producer of the bean. Therefore, it is crucial to monitor product compliance with Brazilian and international regulations, especially regarding pesticide residues used in coffee plantations. This study describes the optimization and validation of a method for the determination of glyphosate, aminomethylphosphonic acid, and glufosinate in green coffee beans. The extraction process was optimized using water and methanol, both acidified with 1% (v/v) formic acid. Sample purification involved a combination of liquid-liquid extraction with a mixture of methyl tert-butyl ether and ethyl acetate (9:1, v/v) and dispersive solid-phase extraction using 75 mg of C18. The extract was analyzed by LC-MS/MS using a Waters’ anionic polar pesticide column. Method validation was conducted in accordance with the guidelines established in the SANTE/11312/2021 guide. Recovery percentages ranged from 76–77% for glyphosate, 70–77% for AMPA, and 81–87% for glufosinate. All variation coefficients were below 20%. The detection and quantification limits determined for the analytes ranged from 0.01 to 0.02 mg kg−1 and 0.02 to 0.04 mg kg−1, respectively. The validated method was used to analyze real coffee samples from plantations where glyphosate was applied using different treatment methods. Of the samples analyzed, only 4 showed glyphosate contaminations above the maximum residue limit established by the European Union. However, none of the samples exceeded the maximum residue limit set by Brazilian legislation, which is ten times higher than the European limit. There was no evidence of a direct influence of nozzle types used or the seasonality on the herbicide residue content in the green coffee beans. Although, the major susceptibility of the Coffea arabica species has been observed by the product application. Additionally, the analysis of fermented coffees from plantations that used glyphosate showed no relationship between residue concentration and the fermentation process of coffee fruits.