乙醇-K_2HPO_4-KH_2PO_4双水相萃取固体基质室温燐光法测定色氨酸

Determination of tryptophan by solid surface room temperature phosphorimetry after aqueous two-phase extraction based on ethanol-K_2HPO_4-KH_2PO_4

提出了一种基于乙醇-电解质-水体系双水相萃取、固体基质室温姘光法（SS—RTP）测定色氨酸的新方法：将适量电解质和乙醇加入试液中，离心后用SS-RP测定上相中的色氨酸。在最佳萃取体系乙醇-K2HPO4-KH2PO4-H2O中，测定色氨酸的线性范围1．0×10^-7-2．0×10^-6mol／L、检出限5．4×10^-9mol／L（S／N=3）。用于大豆、大米、玉米和竹笋中色氨酸的测定，相对标准偏差2．2％～3．3％，与荧光法比较，相对误差-3．3％～3．2％。

Based on ethanol-electrolyte-H20 system, a new aqueous two-phase extraction was developed for the determination of tryptophan coupled with solid surface room temperature phosphorimetry （ SS-RTP）. The procedure is as follows： after centrifuged, the sample solution added suitable amount of electrolyte and ethanol was divided into two phases, and then the enriched tryptophan in the upper phase was determined by SS-RTP. In the optimal system of ethanol- K2HPO4-KH2PO4-H2O, the calibration curve of the analyte gave a linear dynamic range of 1.0×10^-7-2.0×10^-6mol/L with a detection limit of 5.4×10^-9mol/L （S/N = 3）. Combined with SS-RTP, this extraction technique has been successfully applied to the analysis of tryptophan in soybean, rice, corn and bamboo shoot with relative errors of - 3.3 % - 3.2 % as compared with fluorospectrophotometry and relative standard deviations of 2.2 % -3.3 %. The method has outstanding advantages such as simple operation, low consumption of extraction solvent, high extraction effieieney, little interference with analyte, low detection limit, and low toxicity.