Evaluación de la contaminación por aflatoxinas B1, B2, G1 y G2 en maíz amarillo duro

The aim of the present study was to evaluate the natural occurrence of aflatoxins B1, B2, G1, and G2 in kernels of maize from the province of “Los Ríos”, Ecuador, applying a previously methodology validated in the laboratory of “Analysis Service and Food Research” from INIAP. For the purpose, immunoaffinity columns and High Performance liquid chromatography (HPLC) with electrochemical post column derivatization was used. The evaluation of the parameters of validation stablished that the proposed analytic method is selec- tive and did not showed interference in analyzing the four types of aflatoxins. The detection limits of the method were 0.25, 0.36, 0.17 y 0.23 μg/kg, and the quantification limits were 0.83, 1.20, 0.29 y 0.75μg/kg, for aflatoxin B1, B2, G1 and G2, respectively. The precision and accuracy of the method was evaluated using samples of maize artificially contaminated with three levels of aflatoxins in triplicate in three different days, showing that the applied method has a Repeatability standard deviation percentage from 1.14 to 2.31%. The repro- ducibility ranged from 2.66 to 10.90%, with an accuracy as a percent recovery of 71.41, 74.92, 75.82, and 76.87 for aflatoxins B1, B2, G1 and G2, respectively. The aflatoxins were evaluated to 61 kernel samples taken directly from farmers’ fields. 50% of the samples showed aflatoxin B1 contamination ranged from 1.03 to 193.54 μg/kg; 12% showed aflatoxin B2 contamination ranged from 1.24 to 8.26 μg/kg. The incidence of G1 Aflatoxin was of 5% ranged from 1.25 to 7.57 μg/kg. The samples did not show contamination with aflatoxin G2. La presente investigación se realizó con el objetivo de evaluar la ocurrencia natural de aflatoxinas B1, B2, G1 y G2 en maíz duro procedente de la provincia de Los Ríos, Ecuador, aplicando una metodología previamente validada en el laboratorio de Servicio de Analisis e Investigación en Alimentos del INIAP. Para esto se empleó columnas de inmunoafinidad y Cromatografía Líquida de Alta Resolución (HPLC) con derivatización electroquímica post-columna. La evaluación de los parámetros de validación permitió establecer que el método analítico propuesto es selectivo y no mostró interferencias para el análisis de los cuatro tipos de aflatoxinas. El método presentó límites de detección de 0,25; 0,36; 0,17 y 0,23 μg/kg, y límites de cuantificación de 0,83; 1,20; 0,29 y 0,75 μg/kg, para aflatoxina B1, B2, G1 y G2, respectivamente. La precisión y exactitud del método se evaluó empleando