苯酚、马尿酸和甲基马尿酸的反相高效液相色谱分析

本文提出了人体内苯、甲苯和二甲苯的代谢产物苯酚、马尿酸和甲基马尿酸的反相高效液相色谱分析法,讨论了其保留机制和样品预处理技术.以ODS为固定相,甲醇-水-醋酸为流动相时可实现良好分离.方法回收率为97.3%,相对标准偏差为1.02%.提出的方法可用于尿样分析,适用于临床与职业病防治的监测分析.     

An electropolymerized aniline-based fiber coating for solid phase microextraction of phenols from water

An aniline-based polymer was electrochemically prepared and applied as a new fiber coating for solid phase microextraction (SPME) of some priority phenols from water samples. The polyaniline (PANI) film was directly electrodeposited on the platinum wire surface in sulfuric acid solution using cyclic voltammetry (CV) technique. The efficiency of new coating was investigated using a laboratory-made SPME device and gas chromatography with flame ionization detection for the extraction of some phenols from the headspace of aqueous samples. The scanning electron microscopy (SEM) images showed the homogeneity and the porous surface structure of the film. The results obtained proved the ability of this polymer as a suitable SPME fiber coating for trapping the selected phenols. Influential parameters affecting the extraction process were optimized and an extraction time of 50 min at 50 °C gave maximum efficiency, when the aqueous sample was saturated with NaCl and adjusted at pH 2. This new coating can be prepared easily in a reproducible manner and it is rather inexpensive and stable against most of organic solvents. The PANI thickness can be precisely controlled by the number of CV cycles. At the optimum conditions, the R.S.D. for a double distilled water spiked with phenol and chlorophenols at ppb level were 4.8-17% (n = 3) and detection limits for the studied compounds were between 0.69 and 3.7 ng ml⁻¹, except for phenol and 4-chlorophenol. The optimized method was successfully applied to some real-life water samples.     

The role of β-cyclodextrin and hydroxypropyl β-cyclodextrin in the secondary chemical equilibria associated to the separation of β-carbolines by HPLC

The use of cyclodextrins (CDs) in HPLC as mobile phase additives provides a flexible alternative for the separation of chemically related compounds because these separations can be performed on conventional columns and are economically advantageous over the use of chiral stationary phases. The present paper describes the influence of the presence of β-cyclodextrin (β-CD) and 2-hydroxypropyl-β-cyclodextrin (HPβ-CD) on the separation of the β-carboline alkaloids norharmane, harmane and harmine. The nature of the stationary phase (reverse phases C₁ and C₁₈) affects the chromatographic separations and also the stability of the inclusion complexes that are developed. The changes in the proportion of the organic solvents at constant concentration of CDs (3 mM for β-CD and 15 mM for HPβ-CD) modify the retention factors (k′) for all alkaloids studied. The nature of the organic solvent in the mobile phase also changes the chromatographic parameters. The logarithm of the capacity factor (k′) is linearly increased with the proportion of water in the hydro-organic mobile phase (ethanolic or methanolic) but the slopes obtained vary depending on the CD added to the mobile phase. The role of competitive equilibria, i.e., chromatographic distribution and inclusion complexes formation is discussed. This paper was presented at XIIIth International Cyclodextrin Symposium. Torino, Italy, May, 14–17, 2006     

Analysis of organic compounds in environmental samples by headspace solid phase microextraction

The analysis of samples contaminated by organic compounds is an important aspect of environmental monitoring. Because of the complex nature of these samples, isolating target organic compounds from their matrices is a major challenge. A new isolation technique, solid phase microextraction, or SPME, has recently been developed in our laboratory. This technique combines the extraction and concentration processes into one step; a fused silica fiber coated with a polymer is used to extract analytes and transfer them into a GC injector for thermal desorption and analysis. It is simple, rapid, inexpensive, completely solvent-free, and easily automated. To minimize matrix interferences in environmental samples, SPME can be used to extract analytes from the headspace above the sample. The combination of headspace sampling with SPME separates volatile and semi-volatile analytes from non-volatile compounds, thus greatly reducing the interferences from non-target compounds. This paper reports the use of headspace SPME to isolate volatile organic compounds from various matrices such as water, sand, clay, and sludge. By use of the technique, benzene, toluene, ethyl-benzene, and xylene isomers (commonly known as BTEX), and volatile chlorinated compounds can be efficiently isolated from various matrices with good precision and low limits of detection. This study has found that the sensitivity of the method can be greatly improved by the addition of salt to water samples, water to soil samples, or by heating. Headspace SPME can also be used to sample semi-volatile compounds, such as PAHs, from complex matrices.     

Simultaneous determination of oxycodone and its major metabolite, noroxycodone, in human plasma by high-performance liquid chromatography

Oxycodone (14-hydroxy-7,8-dihydrocodeinone) is a potent opioid receptor agonist. In the present study, a liquid-liquid extraction-based reversed-phase HPLC method with UV detection was validated and applied for the analysis of oxycodone and its major metabolite, noroxycodone, in human plasma. The analytes were separated using a mobile phase, consisting of acetonitrile and phosphate buffer (8:92, v/v) at a flow rate of 1 mL/min, and UV detection at 205 nm. The retention times for oxycodone, noroxycodone and codein (internal standard) were 14.7, 13.8 and 10.2 min, respectively. The validated quantitation range of the method was 2-100 ng/mL for oxycodone and 10-100 ng/mL for noroxycodone. The developed procedure was applied to assess the pharmacokinetics of oxycodone and its metabolite following administration of a single 20 mg oral dose of oxycodone hydrochloride to one healthy male volunteer.     

SPME-GC-MSD for Determination of Nine Phenyl Compounds in Snow Water in Beijing China

Solid phase microextraction (SPME) then capillary gas chromatography with mass spectrometric detection have been used for determination of nine phenyl compounds in snow water in Beijing City. Headspace extraction with a fiber coated with 100 µm PDMS was used to extract the compounds. Extraction and desorption times were optimized at 8 and 2 min, respectively. Relative standard deviation (RSD) of the analytical method was found to be less than 5%. The linear range was wide and limits of detection were less than 5 ng mL⁻¹ for the nine target analytes. Several phenyl compounds at ng mL⁻¹ levels were detected in snow samples in Beijing, indicating the corresponding air pollution.     

Thermal characteristics of solid-solid phase transitions in long-chain dialkyl ammonium salts

A series of symmetrical dialkyl ammonium salts, DC_nX, has been prepared and characterized with respect to temperature and enthalpy of solid-solid phase transitions, temperature of melting, thermal stability as well as the reversibility of the phase transitions. The number of carbon atoms, C_n, was varied between 8 and 18 and as anions X halides, nitrate, chlorate, perchlorate and hydrogen sulphate had been chosen. In dependence on chain length and anion type transition temperatures from 20 to 100 °C were observed. Mass specific solid-solid transition enthalpies reach values of 185 J g⁻¹, which makes this class of substances attractive for heat storage applications. The influence of anion type on the transition enthalpies is explained in terms of packing requirements, hydrogen bond network formation and contributions from hindered anion rotation.     

Synthesis,characterization, and application of griseofulvin surface molecularly imprinted polymers as the selective solid phase extraction sorbent in rat plasma samples

In present study, an investigation was carried out to develop and validate an analytical method for the selective extraction and determination of griseofulvin (GSF) from plasma samples. For this purpose, a rational approach was made to synthesize and characterize the surface molecularly imprinted polymers (SMIPs). The SMIPs were utilized as solid phase extraction (SPE) sorbents. The SMIPs were prepared by using GSF as template molecule on the surface of modified silica particles through a non-covalent technique. The particles demonstrated high adsorption capacity (119.1 µg/mL), fast adsorption equilibrium time (30 min) and good recognition selectivity for the template drug. The scanning electron microscopy and infrared spectroscopy were used to explain the structural and morphological characteristics of the SMIPs and surface non-imprinted polymers. The SPE method was combined with HPLC for plasma analysis. The method validation results demonstrated that the established method possessed good linearity for GSF ranging from 0.1 to 50 µg/mL (R² = 0.997). The limit of detection for this method was 0.02 µg/mL for rat plasma samples. The recoveries of GSF from spiked plasma samples were (90.7–97.7%) and relative standard deviations were (0.9–4.5%). Moreover, the SMIPs as selective SPE sorbent can be reused more than 8 times which is a clear advantage over commercial SPE sorbents. Finally, the usefulness of the proposed strategy was assessed by extraction and detection of GSF in real rat plasma samples.     

环己烷催化氧化制取顺酐和醋酸的催化剂研究

为研究气态环己烷催化氧化制取顺酐及醋酸的新反应，采取不同的方法制备了系列固体VPO催化剂.借助XRD、FT-IR对催化剂进行了主体晶相确定，用氧化还原滴定方法测定了不同晶相催化剂中钒的平均氧化数.结合催化反应的活性评价，发现催化剂主体晶相、结晶度、活化气氛和催化剂的V4＋/V5＋比均对目标反应的催化活性产生影响，5种催化剂中以(VO)2P2O7晶相催化剂的活性为最高.