Measuring amino acids in legume samples

Amino-acid analysis has a long history in the characterisation of protein-based products, since it provides information on the product protein concentration without referring to an external protein standard and it is independent from the shape and the charge of the protein. In addition, a given amino-acid composition can confirm sample identity and gives a measure of sample purity. The procedure presented herein details the process of determining the content of amino acids by high performance liquid chromatography (HPLC) using the internal standard method. The principle is based on the reaction of primary amines with o-phtalaldehyde (OPA) in the presence of mercaptoethanol to form 1-thio substituted 2-alkyl isoindoles. The advantage of the derivatization is that they involve a rapid reaction and high sensitivity and the isoindoles thus obtained are well suited for HPLC separation. Identifying the amino acid composition of germplasms will enable to identify germoplasms with more balanced profiles, which could have important impacts for human and animal health.The information presented here has been thoroughly researched and is believed to be accurate and correct. However, the authors cannot be held legally responsible for any errors. There are no warranties, expressed or implied, made with respect to the information provided. The authors will not be liable for any direct, indirect, special, incidental or consequential damages arising out of the use or inability to use the content of this publication