Determination of amino acids in selenium-enriched yeast by gas chromatography-mass spectrometry after microwave assisted hydrolysis.

A simple, rapid microwave digestion procedure for protein hydrolysis preceding the determination of amino acids in yeast using gas chromatography-mass spectrometry (GC-MS) is described. Protein hydrolysis was performed in a focused microwave using 4M methanesulfonic acid (MAS). Amino acids were derivatized with methyl chlorofomate (MCF) and extracted into chloroform prior to GC-MS analysis. The microwave parameters, including power, temperature and heating time, were optimized. It was found that temperature and heating time were the most influential factors. A total of 17 amino acids were determined in selenium-enriched yeast with use of standard addition calibration. Limits of detection and quantitation (LODs/LOQs) of the amino acids measured were in the sub-nmol range, suitable for monitoring of amino acids in yeast and other food products.