| Sample preparation is used to separate matrix and the coexistence of distractors, and preconcentrate of component, thus, it can improve the detection sensitivity. Sample pretreatment is time consuming and makes error easily, therefore, it is the key step in the complex sample analysis. The traditional methods, such as liquid-liquid extraction, headspace solid-phase microextraction, salting out method, suffer from the disadvantage of tedium、large consumption of solvent、long processing time and easy to lose and so on. Solid phase extraction (SPE) is mainly by functional group on the adsorbent and the target compound forces between functional groups, in order to maintain the target on the adsorbent, while the sample matrix which was not adsorbed will get through solid-phase extraction plant. Solid phase extraction is a common sample pretreatment technology which overcomes the difficulty of processing large sample volume, and uses a little of toxic organic solvent and avoid emulsifying and time-consuming. Moreover, it can easily and effectively separate the analyte and the interfering component. SPE coupled with chromatography achieve the optimum combination of sample preparation and analysis of separation, and avoid interference with human factors, so as to improve the accuracy and sensitivity of measurement.This work combines solid phase extraction with capillary electrophoresis (CE), has established a new sample pretreatment method to analyse antibiotics and pesticide residues in environment water samples. The main research contents are as follows:(1) A solid-phase extraction (SPE)-capillary electrophoresis method was developed for the determination of tetracyclines residues in surface water. The aim of this study was to evaluate the adsorption specificity of ordered mesoporous carbon (OMC) as solid phase extraction (SPE) adsorbents with tetracyclines (tetracycline, oxytetracycline and doxycycline) as model analytes. The parameters affecting the adsorption efficiency were investigated in detail. The optimal extraction conditions were as follows:5mg OMC as adsorbent,4mL mixture of methanol and acetonitrile (v/v,1:1) as eluent (pH10.0) at a speed of0.7mL min-1, sample pH10.0. Combined with optimal separation conditions of capillary electrophoresis, the linear range of the analytes varied from3000to11000μg L-1, and relative standard deviations of peak area of each component were less than8.5%(n=5) intra-day analyses. The limits of detection and the average recovery (for tetracycline, oxytetracycline and doxycycline) were in the range of1.96～2.14μg/mL and46.7～93.6%, respectively. This work demonstrates that OMC was a potential adsorbing material in preconcentrating oxytetracycline and doxycycline from environmental samples.(2) A magnetic solid-phase extraction (MSPE)-capillary electrophoresis method was developed for the determination of sulfonamide antibiotics in water samples. A magnetic graphene composites (G/Fe3O4) was synthesized by a facile one-pot solvothermal method and the properties of the magnetic composites were characterized by X-ray diffraction and FTIR. The magnetic graphene composites, as an adsorbent, had selective adsorption performance. Under the optimal conditions: sample volume200mL (pH3.0),20mg G/Fe3O4as adsorbent,0.5mL acetonitrile as eluent, extraction time10min. The limits of detection for four SAs were in the range of0.89～2.31μg L-1. The relative standard deviations (RSDs) for intra-day and inter-day analyses were in the range of4.9～8.5%and4.0～9.0%, respectively. The proposed method was effectively used in the preconcentration and determination of sulfonamide antibiotics in the environmental water samples with the mean recoveries that varied from70.5to111.2%. Relative standard deviations were3.2-13.4%.(3) A magnetic solid-phase extraction (MSPE)-capillary electrophoresis method was developed for the determination of triazine pesticides residues in surface water. The adsorption specificity of magnetic graphene composites (G/Fe3O4) and the parameters affecting the adsorption efficiency were investigated in detail. It turned out that the obtained magnetic composites as SPE adsorbent for MSPE endowed the method with the good enrichment of trace amount of triazine pesticides. Under the optimal conditions:sample volume200mL (pH7.0),20mg G/Fe3O4as adsorbent,0.5mL acetone as eluent, extraction time15min. The limits of detection for four triazine pesticides were in the range of0.91～3.12μg L-1. The relative standard deviations (RSDs) were in the range of4.9～8.5%and4.0～9.0%, for both intra-and inter-day analysis. The proposed method was applied for the preconcentration and determination of triazine pesticides in the environmental water samples (river water and tap water) with mean recoveries in the range of70.4～117.3%. Relative standard deviations were3.2～11.5%. This method could satisfy the requirements for the determination of different triazine pesticide residues in real samples. |
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