Determination of amino acids in Sargassum fusiforme by high performance capillary electrophoresis

High performance capillary electrophoresis (HPCE) was developed for quantitative determination of 18 phenylthiohydantoin (PTH)-amino acids. The influence of electrolyte concentration, pH, organic modifier and applied voltage on HPCE performance was investigated. The HPCE separation of a PTH-amino acids mixture was much improved by adding organic modifier and Tris-boric acid buffer to the run buffer. After optimization of the method, 17 PTH-amino acids in a solution containing 18 PTH-amino acids could be separated using 400mmoll(-1) Tris-boric acid, 1.0mmoll(-1) diethylamine at pH 9.5 adjusted with 0.1moll(-1) NaOH as a run buffer, voltage of 25kV was applied, temperature was maintained at 25 degrees C, detection wavelength was 254nm. The precision (n=7) of this method is less than 3.2% (peak area) and 1.1% (migration time) of relative standard deviation (R.S.D.). Linearity was established over the concentration range 50-1000muM of each derivative, with correlation coefficients (r) ranging between 0.9904 and 0.9993. The detection limits (S/N=3) range from 2 to 48mumoll(-1). The method was applied to determine amino acids in Sargassum fusiforme, a marine algae collected from Tongtou County of Zhejiang Province in China with satisfactory results.