Aflatoxin M1 determination and stability study in milk samples using a screen-printed 96-well electrochemical microplate

A highly sensitive method for the determination of aflatoxin M-1 (AFM(1)) is described that involves the use of a disposable multichannel microplate coupled to intermittent pulse amperometry (IPA) for immunosensor development based on a direct competitive assay. Immunoassay parameters were evaluated and optimized to establish an electrochemical enzyme-linked immunosorbent assay (ELISA) procedure for AFM(1) in milk samples. The suitability of the immunosensors for the direct analysis of the toxin in milk was assessed. AFM(1) was measured with a working range of 5-250 pg mL(-1) and a detection limit of 1 pg mL(-1). Good recovery values (90-105%) were obtained. The method was used to study the recovery of this toxin in frozen (-30 degrees C) or lyophilized (4 degrees C) milk samples stored for up to 3 months. A significant, but variable, decrease (>50%) of the measured AFM(1) concentration with respect to the initial toxin contamination levels was found. (C) 2009 Elsevier Ltd. All rights reserved.