[Determination of main free amino acids in Banlangen Keli by UPLC]

To establish a quantitative method with precolumn derivatization for determining the contents of six common amino acids in Banlangen Keli by UPLC.

Using 6-acetamido-4-hydroxy-2-methyl quinoline as the derivating agent, we determined the contents of arginine, threonine , alanine, gamma aminobutyric acid, proline, and valine. The UPLC analysis was performed on a Waters AccQ Tag TM Ultra C18 column (2.1 mm x 100 mm, 5 microm) with mobile phase AccQ Tag Ultra Eluent A and AccQ Tag Ultra Eluent B gradient elution at a flow rate of 0.7 mL x min(-1). The column temperature was 55 degrees C and detection wavelength was 260 nm.

The linear ranges of arginine, thremine, alanine, gamma aminobutyric acid, proline, and valine were 4. 15549.86 microg (r = 0.999 9), 0.595-5.95 microg (r = 0.999 8), 0.445-4.45 microg (r = 0. 999 9), 0.515-5. 15 pg (r = 0.999 9), 8.858-106.3 microg (r = 0.999 9) , 0.585-5. 85 microg (r = 0.999 8). Their average recoveries were 100.6%, 98.35%, 100.2%, 98.44%, 98.34%, 98.18% with RSD 1.8%,1.9%, 2.0%, 2.4%, 1.5% and 2.0%, respectively (n = 6). The contents of amino acids were different in samples from five productive enterprises.

The method is efficient, good reproducible, sensitive, and accurate.