Simple and rapid quantitative determination of lysinoalanine and protein hydrolysate amino acids by high-performance liquid chromatography after derivatization with dansyl chloride

Summary A rapid and simple method for the determination of both lysinoalanine (LAL) and protein hydrolysate amino acids after derivatization with dansyl chloride (5-dimethylaminoaphtalene-1sulfonyl chloride) and separation with RP-HPLC (UV detection) is presented. LAL is analysed in less than 15 minutes and complete separation of 22 amino acids is achieved in less than 30 minutes using single linear gradients of solvents (phosphate buffer and acetonitrile). Quantitative results obtained by HPLC compare well with results of the ion-exchange chromatography (amino acid analyser). The importance of the duration of the derivatization reaction and of the excess of reagent is discussed. As examples, the results of the determination of LAL in two samples of base treated α-casein and 22 samples of soy protein and the results of the analysis of amino acids in two balanced diet mixtures are presented. Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984