Fully automated precolumn derivatization, on-line dialysis and high-performance liquid chromatographic analysis of amino acids in food, beverages and feedstuff

A reliable, high throughput method is described for the routine analysis of amino acids in food, beverages and feedstuff: A fully automated sample processor performs precolumn derivatization of both primary and secondary amino acids with o-phthalaldehyde-3-mercaptopropionic acid and 9-fluorenylmethyl chloroformate (FMOC), respectively. Following dilution and derivatization, an on-line dialysis step is performed to remove macromolecular, microparticulate and insoluble interferents resulting from complex matrices and the FMOC derivatization. The optimization strategies for sample preparation and HPLC are discussed in this work. Twenty-five amino acids (including cystine) present in food products are separated in 24 min using a simple one-step binary gradient, with an excellent resolution and outstanding reproducibility. Analytical data are provided both for standard solutions and real samples. (C) 1998 Elsevier Science B.V.