Simultaneous Determination of Amino Acids in Hippophae rhamnoides L. with Pre-column Derivatization by HPLC

A novel, sensitive and selective HPLC-FLC method coupled with pre-column derivatization was developed for amino acid determination in Hippophae rhamnoides L. fruit from Qinghai-Tibetan plateau. The method is based on the derivatization reaction of amino group with 2[2-(dibenzocarbazole)-ethoxylethyl chloroformate (DBCEC) and the derivatives could be measured at 390 nm (excitation wavelength: 300 nm). Detection limits (calculated as the signal-to-noise ratio 3:1) were 12.85-51.68 mol for the labeled amino acids. Linearity was observed with coefficients > 0.9991 and the recoveries ranged from 92.7-105.4 %. Results in this research showed that the amount of essential amino acids accounted for 70.42 % of free amino acids and 22.68 % of the total amino acids, respectively, which benefits people's health through drinking the juice or eating the related products. Proline was dominating among free amino acids in samples, which plays a vital role for Hippophae rhamnoides L. in resisting to drought, tolerating soil salinity and lowing temperature in Qinghai-Tibetan plateau.