Intralaboratory optimization and validation of a method for patulin determination in grapes by Thin-Layer Chromatography

Abstract

The aim of this work was to optimize and validate, by intralaboratorial procedures, a method for the determination of patulin in grapes by thin-layer chromatography. The steps of extraction, cleanup, detection and quantification were optimized. For the validation of the method, recovery assays with standard solutions and artificially contaminated samples were carried out. The mean recovery and the variation coefficient were 65.4% and 7.58%, respectively. The optimized conditions were: 50 mL of grape juice, three extraction stages (with 100 mL of ethyl acetate in the first stage and 50 mL in second and third stages), and 100 µL of ethanol to solubilize the extract. The solvent-system used was toluene - ethyl acetate - formic acid (6:3:1), and 0.5% MBTH in 5% formic acid was sprayed on the plates to intensify the fluorescence. The visual detection and quantification limits were 7.44 ng and 15.87 µg.kg-1, respectively. The optimized and validated method demonstrated sufficient efficiency for adoption in the monitoring of patulin in grape.