SEC-MS/MS determination of amino acids from mango fruits and application of the method for studying amino acid perturbations due to post harvest ripening

A simple and sensitive size exclusion chromatography - liquid chromatography tandem mass spectrometry (SEC-MS/MS) based analytical method was developed for the quantification of free amino acids from mango fruit pulp samples. The pulp samples were extracted with 70:30 acetonitrile:water containing 0.05 mol/L formic acid and treated with activated charcoal to remove the phenolic and hydrophobic impurities. The amino acids were isolated by strong cation exchange process and quantified by SEC-MS/MS. The method was validated for linearity, the limit of detection and limit of quantification. The LOQ values were observed in the range of 0.2-145 ng/g at 10:1 signal to noise ratio and the interday and intraday precisions were below 15%. The developed method was applied for the analysis of amino acids in mango fruits ripened with ethylene, calcium carbide and ethephon ripening agents. Alanine was observed as major amino acid and other amino acids showed significant changes, which were studied by ANOVA and principal component analysis (PCA). The PCA studies showed that the fruits ripened with calcium carbide are similar to that of naturally ripened fruits.