Aminosäurebestimmung in Nahrungsmitteln durch Chromatographie an Stärkesäulen

Abstract

Starch column chromatography of amino acids is discussed. Losses of amino acids occur during hydrolysis, particularly in presence of high carbohydrate content. Under these conditions hydrolysis is first carried out with formic acid, peptides, amino acids and amides are precipitated with mercury carbamate and hydrolysis is then continued; tryptophan and cysteine are lost by this procedure. A fraction collector using a syphon is described. Various starches were tested, and the characteristics of the most satisfactory column described. Acetate buffer is preferred to citrate buffer in the ninhydrin solution. The mean deviation in a series of 6 hydrolysates averaged [plus or minus] 4.5% of the amino acid value concerned. The sum of the N contents for the amino acids in a synthetic mixture was 100.9%. When a casein hydrolysate was examined the loss was 2-5%, and in a wheat flour and barley hydrolysate it was 5-10%. This deficit was regarded as being not due to loss in the analysis.