Microalgae amino acids: Method validation using gas chromatography coupled to mass spectrometry

This study aimed to develop a method for determining protein amino acids in microalgae using gas chromatography coupled with mass spectrometry. To efficiently hydrolyze the microalgal proteins and obtain the amino acids, a rotational central composite design was employed with two independent variables: reaction temperature (99.7–170.3 ºC) and hydrolysis time (1.1–27.9 h). The amino acids were derivatized with N-methyl-N-(trimethylsilyl)trifluoroacetamide and analyzed on a gas chromatograph coupled to a mass spectrometer. Subsequently, the optimized condition was validated and used to characterize the amino acid profile of Spirulina sp. This validation adhered to the criteria set by ANVISA RDC No. 166 and European Union guidelines (SANTE 11312/2021) and consisted of assessing selectivity, limits of detection and quantification, linearity, working range, precision, and accuracy. Nineteen protein amino acids were detected and quantified from the biomass of Spirulina sp., and all validation parameters yielded satisfactory results. Our findings showed that using gas chromatography coupled with mass spectrometry proved effective and reliable for determining protein amino acids in microalgae.