Study On The New Systems And Methods For Spectrometric Determination Of Phenylalanine And Orthophosphate

The development of modern spectrometry has provided a large number of analytical methods and tools for the researches in both life science and environmental science. In this paper, a novel solid fluorimetric method based on the immobilization of reagents by sol-gel technology and a fluorimetry based onβ-cyclodextrin-functionized CdTe quantum dots were developed for the determination of phenylalanine, which can be potentially applied to the phenylketonuria screening of infants. In addition, for the detection of orthophosphate in environmental waters, a new strategy based on reagent-immobilized poly (vinyl alcohol) films was studied and established. The dissertation consists of four chapters as follows:Chapter 1:ReviewThe progress about phenylalanine and phosphate detection in recent years both at home and abroad was reviewed. The topic of the dissertation was proposed based on the existing literatures.Chapter 2:Development of a novel solid fluorimetric method for the determination of phenylalanine using reagent-immobilized sol-gel filmsA novel solid fluorimetric method for the determination of phenylalanine was developed based on immobilizing the reagents on the surface of filter paper with sol-gel technology, the fluorescence enhancement of phenylalanine-ninhydrin system by Eu(III) was investigated. Under the optimum conditions, the fluorescence intensity of phenylalanine-ninhydrin-Eu(Ⅲ) system is linearly proportional to the concentration of phenylalanine in the range of 5×10^-5～2×10^-3 mol L^-1, and the limit of detection is 5.2×10^-6 mol L^-1. The relative standard deviation is 2.6% (n=10). The method has been applied to the determination of phenylalanine in artificial serum, and the recovery is between 94.7% and 104.6%. Chapter 3:A novel fluorimetric determination of phenylalanine based onβ-cyclodextrin-functionized CdTe quantum dotsA new fluorimetric method for phenylalanine quantification was developed based on the fluorescence enhancement ofβ-cyclodextrin-functionized CdTe quantum dots (β-CD-CdTe QDs). CdTe quantum dots were functionized byβ-cyclodextrin with ultrasonic-assisted reaction, and the effects of reaction parameters on the fluorescence ofβ-CD-CdTe QDs were systematically studied. Under the optimum conditions, the fluorescence intensity of theβ-CD-CdTe QDs was linearly proportional to the concentration of phenylalanine in the range of 0.5×10^-6～1.0×10^-4 mol L^-1 and the limit of detection was 3.7×10^-6 mol L^-1. The relative standard deviation is 1.04% (n=10). The proposed method has been applied to determination of phenylalanine in human serum, and the recovery is between 97.8% and 91.9%. This method can be potentially applied to the screening of newborn phenylketonuria.Chapter 4:A modified spectrophotometric determination of orthophosphate with reagent-immobilized poly (vinyl alcohol) filmsA simple and rapid method for the determination of orthophosphate was developed in this study. The method is based on a reagent-immobilized poly (vinyl alcohol) (PVA) film which was prepared by temporary immobilization of sensitive reagents on the glass slide. The preparation conditions of the film were investigated in detail. Under the optimum conditions, the absorbance is linearly proportional to the concentration of phosphorus from 0.65 to 8.1μmol L^-1 and the limit of detection is 0.5μmol L^-1 of phosphorus. The relative standard deviation is 2.9% (n=10). The proposed method has been effectively used for the determination of orthophosphate in various water samples.