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 400 mmol l−1 Tris–boric acid, 1.0 mmol l−1 diethylamine at pH 9.5 adjusted with 0.1 mol l−1 NaOH as a run buffer, voltage of 25 kV was applied, temperature was maintained at 25 °C, detection wavelength was 254 nm. 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 50–1000 μM of each derivative, with correlation coefficients (r) ranging between 0.9904 and 0.9993. The detection limits (S/N = 3) range from 2 to 48 μmol l−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.