Determinação de ocratoxina A em uva e produtos processados por cromatografia líquida de alta eficiência

Abstract

Mycotoxins are toxic substances produced by fungi that can be found in many foods, such as grapes and processed foods (grape juice, wine and raisins). Ochratoxin A (OTA) naturally occurring belongs to the group of the ochratoxins and its structure is considered to be the most toxic. The analysis of this mycotoxin is performed using liquid-liquid extraction, but this method has a high solvent consumption and needs a cleaning step of the extracts before quantitative analyzes. Studies have been conducted using immunoaffinity columns. However, this technique presents high costs. OTA detection is usually performed by high performance liquid chromatography coupled to the fluorescence detector and mass. Given this scenario, the present work aimed to optimize and validate an alternative analytical method for analysis of ochratoxin A in grapes and processed products. For this, we used two extraction techniques (liquid-liquid partition at low temperature and solid-liquid purification at low temperature) for identification and quantification of ochratoxin A in samples of grape juice, wine, raisins and pink grapes. The experiments were performed at the Research Laboratory of Agrochemistry ICA / UFMG. The influence of ionic strength, pH and the mode of homogenization in the percentages of extraction of ochratoxin A were evaluated. The analyzes were conducted by high performance liquid chromatography with ultraviolet detector (HPLC-UV). The techniques showed extraction percentages higher than 66%, and standard deviation of less than 10%. Ochratoxin A was quantified as derivatized with lower detection limits of 12.5 mg kg-1 to the solid matrices and 6.25 g L-1 for liquid matrices. The limits of quantification were 41.63 mg kg-1 and equal to 20.88 mg L-1, respectively. The chromatographic response was linear for ochratoxin A derivatized with determination coefficient higher than 0.99 in all four matrices analyzed.