CHROMATOGRAPHIC DETERMINATION OF AMINO-ACIDS BY PRECOLUMN DERIVATIZATION USING 1,2-NAPHTHOQUINONE-4-SULFONATE AS REAGENT

A new method based on the pre-column derivatization of amino acids wit h 1,2-naphthoquinone-4-sulfonate followed by the chromatographic separ ation, on a C-18 column, of the derivatives formed is proposed. The re action is developed at pH 10 and the reaction mixture is thermostated at 65 degrees C for 5 min. An elution gradient with seven steps based on increasing the percentage of acetonitrile separates common amino ac ids present in protein hydrolysates. For an injection volume of 50 mu l, the linear range of the method for glycine was up to 20 nmol, its p recision expressed as R.S.D. was 2.6% and the detection limit was 60 p mol. The method has been applied to the determination of amino acids i n hydrolysates of feed samples. Results obtained by the method propose d show satisfactory agreement with those given by the standard method.