SIMULTANEOUS RP-HPLC-DAD DETERMINATION OF DANSYL AMINO ACIDS IN CHEMICALLY TREATED HUMAN HAIR

A simple, rapid, and reliable reversed phase high-performance liquid chromatographic (RP-HPLC-DAD) method for the analysis of 19 amino acids in the protein hydrolysate of chemically treated hair was developed. The pre-column dansylation and RP-HPLC separation were optimized and peak resolution was improved as compared to previously published HPLC methods. The developed method showed excellent linearity for all tested amino acids in the concentration range 0.05-0.5 mmol/l. The obtained results show that the concentration of all amino acids detected in bleached hair decreases with increasing hydrogen peroxide concentration. This is most significant for cystine compared to virgin hair. Higher amounts of the typical amino acids of keratin were measured after exposure of hair to protein treatments. The method has been shown to be very useful for amino acid analysis in the protein hydrolysate and it can also be used for establishing the amino acid profiles of other protein samples using this optimized procedure.