Fast determination of 26 amino acids and their content changes in royal jelly during storage using ultra-performance liquid chromatography

A rapid ultra-performance liquid chromatography (UPLC) method was developed for feasible separation and quantification of 26 amino acids in royal jelly. The analysis was performed on Acquity UPLC system with Acquity UPLC AccQ·Tag Ultra Column within 8 min. The correlation coefficient values (r2 > 0.9978) indicated good correlations between the investigated compounds’ concentrations and their peak areas within the test ranges. The limits of quantitation and detection of 26 amino acids were 42.7–235.1 ng/mL and 12.9–69.3 ng/mL, respectively. The recoveries ranged from 90.1% to 100.9% and the overall relative standard deviations for intra- and inter-day were lower than 2.8%. The results showed that UPLC was a powerful tool for the analysis of amino acids in royal jelly. The method was also applied to quantitatively determine free amino acid (FAA) and total amino acid (TAA) profiles in RJ samples stored at different temperatures (−18 °C, 4 °C and 25 °C) for different time intervals (1, 3, 6 and 10 months). Results showed that the average contents of FAA and TAA in fresh royal jelly were 9.21 mg/g and 111.27 mg/g, respectively; the major FAAs were Pro, Gln, Lys, Glu, and the most abundant TAAs were Asp, Glu, Lys and Leu. Although the concentration of most FAAs and TAAs showed no significant difference during storage, contents of total Met and free Gln decreased significantly and continuously, and might be a parameter to predict the quality of royal jelly.