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Determination of aflatoxin M1 using a dialysis-based immunoaffinity sample pretreatment system coupled on-line to
A Farjam1, N C van de Merbel, A A Nieman
1Department of Analytical Chemistry, Free University, Amsterdam, Netherlands.
Abstract:
A liquid chromatographic column-switching system containing a dialysis unit and an anti-aflatoxin immunoaffinity precolumn (immuno precolumn) is described for the automated determination of aflatoxin M1 in milk samples. Both a flat membrane dialysis unit working according to the flowing donor-flowing acceptor principle and a laboratory made hollow-fibre dialysis unit working according to the stagnant donor-flowing acceptor principle were evaluated. The hollow-fibre unit is superior with respect to repeatability (3% relative standard deviation) and detection limit (10 ng/l for aflatoxin M1 in milk), in spite of the fact that the overall recovery is only 6%. Interfering compounds, which would destroy the activity of the immuno precolumn, are efficiently removed from the system by the dialysis step; a single immuno precolumn can then be used for over 70 milk analyses. No decrease in the performance of either the immuno precolumn or the hollow-fibre dialysis unit is observed.