Hair Amino Acid Analysis

Hair is composed of 20 to 21 amino acids. Analysis of hair requires expertise, as amino acid values may be changed by the preparation technique. The amino acid analysis method is only available at specialized institutes and universities. Although of little value as a diagnostic tool, it can be useful in litigation cases for corroborating patient histories, i.e., to prove whether excessive treatment has occurred or treatment was denied. For example, hair straightened using chemical relaxers typically shows an increase in lanthionine, an amino acid typically absent in normal hair. Similarly, cysteic acid, normally present at approx.< 0.5 mol % is increased in colored or oxidatively bleached hair. In rare cases of excessive bleaching very high levels of cysteic acid will result (Table 3). The technique has important research value to understand chemical mechanisms or hair alteration.