Study on the Sample Preparation of Complex Matrix Analysis of High Performance Liquid Chromatography

Abstract: As an important procedure of chromatography analysis, sample preparation always draws much attention. A simple, rapid and effective sample preparation method for the complex matrix chromatographic analysis is always the target that pursued by the analyst. As for the chromatographic analysis of three kinds complex matrix including toothpaste, medicinal plants and urine, three kinds of sample preparation methods were developed in this paper, including derivatization, cloud point extraction with non-ion surfactant and solid phase extraction by Fe3O4 nano-particles. The main work of this paper is summarized as follows:1, N-(2-phenyl-indolyl)-acetic acid (PIAA), a new fluorescently derivatizing reagent, was used for the determination of diethylene glycol (DEG) by high-performance liquid chromatography with fluorescence detection (HPLC-FLD). DEG was derivatized to ester by using PIAA in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodimide hydrochloride (EDC·HCl) (as dehydrating agent) and the 4-(dimethylamino) pyridine (DMAP) (as base catalyst) in acetonitrile at 60°C for 75 min. The influence of solvent, temperature, catalyst, concentration of labeling reagent, and coupling reagent on the derivatization were investigated. The fluorescence detection was performanced with excitation at 340 nm and emission at 377 nm. Baseline separation was obtained on an UltimateTM XB-C18 analytical column with water/acetonitrile gradient elution, and good linearity was obtained within 0.5-50μg/mL with correlation coefficient of 0.9997. The limit of detection (LOD) was 0.01μg/mL (signal-to-noise ratio=3). The method has been successfully applied to determine DEG in toothpaste sample with satisfactory recoveries ranging from 89.0% to 94.9%. The proposed method was shown to be a promising technique for the determination of DEG with high sensitivity.2, Aristolochic acid I (AA I) and aristolochic acid II (AA II) are the major toxic components in many Aristlolochiaceae plants. In our previous study, we have developed a sensitive and effective method for the determination of aristolochic acids (AAs) coexisting with trace aristololactams (ALs) based on high-performance liquid chromatography with diode array detection–fluorescence detection (HPLC-DAD-FLD). However, a complex derivatization procedure was needed. In this study, a new method based on cloud point extraction was developed for the determination of AA I and AA II in the medicinal plants by high performance liquid chromatography with photodiode array detection. Non-ionic surfactant Triton X-100, which is an environmentally friendly solvent, was used for the micelle-mediated extraction. The conditions of the experiments were optimized. No derivatization procedure was needed. The optimized method was validated with six aistolochiaceae plants. Linearities of around 3 orders of magnitude were obtained with correlation coefficients exceeding 0.9957. The detection limits were decreased to 5 ng/ml. Satisfactory intra-day and inter-day precisions were achieved (RSD less than 3.53%), and the average recovery were in the range of 84.08±3.50%– 109.9±1.00%. The proposed method is simple and green.3, Fe3O4 nanoparticles that is without any modification was used as a new solid phase extraction material, and it was used for the analysis of three kinds of alkaloids (jatrorrhizine, palmatine, berberine) in the urine. The interaction of Fe3O4 and alkaloids may mainly because of the electrostatic adsorption. The conditions of separation, cone voltage and solid phase extraction were optimized. Linearities of around two orders of magnitude were obtained with correlation coefficients exceeding 0.9943, and low limit of detection (0.09 ng/ml) was obtained. And the proposed method may be used in the analysis of alkaloids in environmental matrix…
Key words: High performance liquid chromatography; Derivatization; Cloud point extraction; Solid phase extraction

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