标准物质研制中ICP-AES分析的实验室质量控制

本文从八个方面介绍了标准物质研制中ICP-AES分析的实验室质量控制体系。在此条件下，很好地控制了样品的空白值、精密度和准确度，测定所得数据均被标样研制单位采用。     

Determination of four sulfonylurea herbicides in tea by matrix solid‐phase dispersion cleanup followed by dispersive liquid–liquid microextraction

Matrix solid‐phase dispersion combined with dispersive liquid–liquid microextraction has been developed as a new sample pretreatment method for the determination of four sulfonylurea herbicides (chlorsulfuron, bensulfuron‐methyl, chlorimuron‐ethyl, and pyrazosulfuron) in tea by high‐performance liquid chromatography with diode array detection. The extraction and cleanup by matrix solid‐phase dispersion was carried out by using CN‐silica as dispersant and carbon nanotubes as cleanup sorbent eluted with acidified dichloromethane. The eluent of matrix solid‐phase dispersion was evaporated and redissolved in 0.5 mL methanol, and used as the dispersive solvent of the following dispersive liquid–liquid microextraction procedure for further purification and enrichment of the target analytes before high‐performance liquid chromatography analysis. Under the optimum conditions, the method yielded a linear calibration curve in the concentration range from 5.0 to 10 000 ng/g for target analytes with a correlation coefficients (r²) ranging from 0.9959 to 0.9998. The limits of detection for the analytes were in the range of 1.31–2.81 ng/g. Recoveries of the four sulfonylurea herbicides at two fortification levels were between 72.8 and 110.6% with relative standard deviations lower than 6.95%. The method was successfully applied to the analysis of four sulfonylurea herbicides in several tea samples.     

鲁米诺-双氧水-铬(Ⅲ)化学发光体系测定化探样品中痕量砷

用鲁米诺－双氧水－铬（Ⅲ）化学发光体系结合巯基棉对Ａｓ（Ⅲ）的富集分离，建立了快速的测定化探样品中痕量砷的新方法，检测线性范围为１．０×１０－４～１．０×１０１ｍｇ／Ｌ，检出限为３．４×１０－５ｍｇ／Ｌ。用于实际化探样品测定，相对标准偏差为５．５％～９．０％。     

An improved derivatization method for sensitive determination of fatty acids by high-performance liquid chromatography using 9-(2-hydroxylethyl)-carbazole as derivatization reagent with fluorescence detection

Summary Tagging techniques with reagents used for fluorescent detection for short and long-chain fatty acids using high-performance liquid chromatography are evaluated in terms of the tagging reactions, handing, flexibility, stability of the reagents. Emphasis is given to the applications of the tagging techniques to relatively high molecular mass fatty acids. The fatty acids or carboxylic compounds were derivatized to their corresponding esters with 9-(2-hydroxy ethyl)-carbazole (HEC) in acetonitrile at 60°C with N, N′-carbonyldiimidazole (CDI) as a coupling agent in the presence of 4-dimethylaminopyridine (DMAP). A mixture of esters of C₁−C₂₀ fatty acids was completely separated with 45 min using gradient elution on a reversed-phase C₁₈ column. The maximum fluorescence emission for the derivatized fatty acids is at 365 nm (λ_ex 293 nm). Studies on derivatization conditions indicated that fatty acids react rapidly and smoothly with HEC in the presence of CDI and DMAP in acetonitrile to give the corresponding sensitively fluorescent derivatives. The application of this method to the analysis of long chain fatty acids in plasma is also investigated. The LC separation shows good selectivity and reproducibility for fatty acids derivatives. The relative standard deviations (n=6) for each fatty acid derivative are <5.0%. The detection limits are at 38–57 fmol levels for C₁₄−C₂₀ fatty acids and lower levels for <C₁₄ fatty acids.     

A new molecularly imprinted polymer for selective extraction and pre‐concentration of guaifenesin in different samples: Adsorption studies and kinetic modeling

This paper describes the synthesis of a molecularly imprinted polymer by chemical oxidation of pyrrole as the functional monomer, and at the presence of guaifenesin as the template. The prepared polymer was used as adsorbent in molecularly imprinted solid‐phase extraction followed by spectrophotometric determination. Different parameters in the solid‐phase extraction including sample pH, adsorbent weight, washing solution, and elution solvent were studied to determine optimum conditions for isolation and enrichment of guaifenesin. The results showed guaifenesin was quantitatively adsorbed on the molecularly imprinted polymer at pH 6.0 and completely eluted with an ethanol–water solution (50% v/v). An enrichment factor of four with satisfactory recoveries (87.0–95.0%) was obtained. The solid‐phase extraction columns could be used for up to six consecutive elution‐loading cycles without significant decreases in the analyte recoveries. The method had a dynamic range of 3.0 × 10^?6–1.5 × 10^?4 mol/L with a limit of detection and limit of quantification of 1.4×10^?6 and 4.5×10^?6 mol/L, respectively. The proposed procedure was used for the extraction and determination of guaifenesin in different pharmaceutical formulations, with satisfying results being achieved.     

Electrochemical determination of dopamine and ascorbic acid at a novel gold nanoparticles distributed poly(4-aminothiophenol) modified electrode

A modified electrode is fabricated by embedding gold nanoparticles into a layer of electroactive polymer, poly(4-aminothiophenol) (PAT) on the surface of glassy carbon (GC) electrode. Cyclic voltammetry (CV) is performed to deposit PAT and concomitantly deposit Au nanoparticles. Field emission transmission electron microscopic image of the modified electrode, PAT-Au_nano-ME, indicates the presence of uniformly distributed Au nanoparticles having the sizes of 8-10 nm. Electrochemical behavior of the PAT-Au_nano-ME towards detection of ascorbic acid (AA) and dopamine (DA) is studied using CV. Electrocatalytic determination of DA in the presence of fixed concentration of AA and vice versa, are studied using differential pulse voltammetry (DPV). PAT-Au_nano-ME exhibits two well defined anodic peaks at the potential of 75 and 400 mV for the oxidation of AA and DA, respectively with a potential difference of 325 mV. Further, the simultaneous determination of AA and DA is studied by varying the concentration of AA and DA. PAT-Au_nano-ME exhibits selectivity and sensitivity for the simultaneous determination of AA and DA without fouling by the oxidation products of AA or DA. PAT and Au nanoparticles provide synergic influence on the accurate electrochemical determination of AA or DA from a mixture having any one of the component (AA or DA) in excess. The practical analytical utilities of the PAT-Au_nano-ME are demonstrated by the determination of DA and AA in dopamine hydrochloride injection and human blood serum samples.     

Preparation and Evaluation of Propranolol-Imprinted Monolithic Stationary Phase by In Situ Technique and Application in Analysis of Propranolol in Biological Samples

Abstract

A propranolol molecule-imprinted monolithic stationary phase (MIMSP) was synthesized by in situ technique. The recognition mechanism of the polymers and the influences of some chromatographic conditions were examined by high-performance liquid chromatography (HPLC). The imprinted polymers showed much higher selectivity for β-blockers than the nonimprinted polymers (NIPs) did, which proves the successful preparation of propranolol-imprinted polymers by using an in situ technique. Then, this technique was used to prepare a molecularly imprinted polymer solid-phase extraction column to concentrate propranolol from biological samples. The results showed that the imprinted solid-phase extraction column could selectively enrich and purify propranolol from biological samples, such as plasma.     

A computer program for the optimal ion chromatographic determination of anions in waters

Summary A general form of computer program which can assist in method development for any natural water has been developed. Necessary input data, sequence of main operations, necessary mathematical relationships and the output data are specified. The development of the structure of the computer program was based on experiences with real samples.     

螯合树脂微柱分离富集火焰原子吸收法测定地质样品中的痕量银

利用新合成的螯合树脂聚[4 乙烯苄基 (2 羟乙基硫醚)]制备微型吸附柱,采用螯合树脂微柱分离富集 火焰原子吸收法测定了地质样品中的痕量银。研究了螯合树脂微柱的吸附性能及影响吸附的因素,在稀王水介质中进行吸附,采用酸性硫脲为洗脱剂,以峰面积方式检测,测定Ag 的线性范围0.010～1.0μg mL,灵敏度提高40倍,吸附率在80%,相对标准偏差<4.2%,树脂柱可重复利用100次以上。