Determination of amino acids in Galli Gigerii Endothelium Corneum by HPLC with pre-column derivatization

Hydrolytic amino acids were extracted by acid hydrolysis method, then derivatized with phenyl isothiocyanate (PITC). And the samples were analysed by HPLC on an Ultimate Prime C18 (4.6 mm x 250 mm, 5 microm) column with gradient elution of 0.1 mol x L(-1) sodium acetate buffer solution (adjusted to pH 6. 5)-acetonitrile (93:7) (A) and acetonitrile-water (8:2) (B) at a flow rate of 1.0 mL x min(-1). Column temperature was 40 degrees C and the detected wavelength was 254 nm. Amino acids derivative solution remained stable in 36 hours. The response was linear for 16 amino acids with a correlation coefficient r > 0.999 5. The average recoveries were 98.01% -101.8%. The method is reliable with good accuracy and repeatability, which is useful for the determination of amino acids in Galli Gigerii Endothelium Corneum.