Flow injection monitoring of aflatoxin M1 in milk and milk preparations using filter-supported bilayer lipid membranes.

Abstract

This work describes a technique for the rapid and sensitive electrochemical flow injection monitoring of aflatoxin M1 (AFM1) using stabilized systems of filter-supported bilayer lipid membranes (BLMs). Injections of AFM1 were made into flowing streams of a carrier electrolyte solution, and a transient current signal with a duration of seconds reproducibly appeared less than 10 s after exposure of the lipid membranes to the toxin. The magnitude of this signal was linearly related to the concentration of AFM1, with detection limits at the subnanomolar level. The mechanism of signal generation was investigated by differential scanning calorimetric experiments. The technique was applied for the rapid flow injection determination of AFM1 in milk and milk preparations. The effect of potent interferences such as proteins and lipids was investigated, and the results show that interferences from these milk constituents can be eliminated by modulation of the flow rate of the carrier solution so as not to allow adsorption of these compounds in BLMs. AFM1 could be determined in continuous flowing systems with a rate of at least 4 samples min-1. Repetitive cycles of injection of AFM1 showed no signal degradation during each cycle.