RP-HPLC测定兔血清和脑脊液中甲硝唑含量

 报告了用RP-HPLC测定免血清和脑脊液中甲硝唑浓度的方法，采用ZorbaxC8柱，NaH2PO4水溶液（0.0075mol／L）-甲醇（4:1，PH4.0）为流动相，氢氯噻嗪为内标，检测波长320um。线性范围0.5～80mg／L，最低检出浓度80μg／L（信噪比为3）。     

Determination of amino acids in human cerebrospinal fluid by gas chromatography

In the present study, the use of gas chromatography (GC) for the determination of amino acids in human cerebrospinal fluid (CSF) is described. Although some amino acids may be determined using a packed column following the removal of glucose, the major interfering component, the inadequate resolution of other amino acids from remaining unidentified components results in poor quantitation. The use of wide bore columns improves reproducibility considerably, but still it does not provide sufficient resolution to enable quantitative determination of all amino acids in human CSF. Good reproducibility data, with CV values for all amino acids of 7% or less and recoveries generally between 80% and 100%, can only be obtained using the fused silica open tubular (FSOT) column. Normal amino acid levels are presented for 10 samples of human CSF, which compare well with data previously reported in the literature.     

Trace analysis of methanol in rat serum by headspace high resolution gas chromatography/selected ion monitoring

A high resolution headspace gas chromatography/selected ion monitoring analytical method has been developed for the quantitation of methanol in body fluids. The addition of tetradeuterated methanol as internal standard gives this method high accuracy and reproducibility. The high sensitivity of the mass spectrometer permits analysis of methanol in aqueous solutions at concentrations down to 0.012 mg/l. The analytical procedure described was used to measure serum methanol in rats given 5 mg/kg of this alcohol orally. The method proved suitable for analysis of endogenous levels of methanol and of variations close to endogenous levels.     

Simultaneous determination of keto and non-keto bile acids in human serum by gas chromatography with selected ion monitoring

A reliable method for the simultaneous determination of keto and non-keto bile acids in human serum was developed. Carbonyl substituents of bile acid ethyl esters were converted into methyloxime and hydroxyl substituents into dimethylethylsilyl ethers and the products were analysed directly by capillary gas chromatography with selected ion monitoring using [2H4]chenodeoxycholic and [2H4]3 alpha-hydroxy-7-oxo-5 beta-cholanoic acids as internal standards. The bile acid peaks on the selected ion chromatogram were separated without interference from endogenous substances present in serum. Recoveries of individual keto bile acids added to serum range from 74.4 to 94.7% with a mean of 87.1%. Eight kinds of keto bile acids not previously found in sera of normal subjects, namely 3-oxo-, 3-oxo-7 alpha-hydroxy-, 3-oxo-12 alpha-hydroxy-, 3 alpha-hydroxy-7-oxo, 3 alpha-hydroxy-12-oxo-, 3-oxo-7 alpha,12 alpha-dihydroxy-, 3 alpha,7 alpha-dihydroxy-12-oxo- and 3 alpha,12 alpha-dihydroxy-7-oxo-5 beta-cholanoic acids were identified and quantified. The total concentration of keto bile acids was found to be 0.16 +/- 0.08 nmol/ml and constituted 2.9 +/- 1.5% of that of the usual non-keto bile acids in peripheral venous serum.     

Determination of DiazaCon in quail feed and quail serum by ion pair reversed-phase chromatography.

Liquid chromatographic (LC) methods were developed for quantitating the potential avian contraceptive DiazaCon in quail feed and serum. DiazaCon was extracted from ground quail feed with basic n-butyl chloride. The n-butyl chloride extract was evaporated to dryness. The DiazaCon residues were dissolved in an aqueous methanolic ion pairing solution and quantitated by LC at 206 nm. Avian sera was combined with an equal volume of a pH 4 aqueous solution of ion pairing reagent and filtered to remove interfering proteins. DiazaCon was quantitated by LC. Mean recoveries for 500 and 2000 ppm fortified feed were 89.1 and 91.0%, respectively. The mean recovery for sera fortified at 5 levels ranging from 35 to 2000 ppm was 84.9%. Method limits of detection were approximately 14 and 13 ppm for feed and sera, respectively.     

Determination of 112 halogenated pesticides using gas chromatography/mass spectrometry with selected ion monitoring

A procedure for the analysis of 112 halogenated pesticides that do not contain phosphorus has been developed. The procedure uses gas chromatography with a mass selective detector (GC-MSD), electron impact ionization, and selected-ion monitoring. This GC-MSD procedure provided lower limits of quantitation and provided increased confirmational data compared to the traditional element-selective GC procedures that are commonly used for the detection of this class of pesticides. These analytical improvements were demonstrated by the 25 pesticides that were detected at < or =50 ng/g levels in a variety of fruit and vegetable matrixes using this procedure that were missed by the traditional element selective GC procedures. Validation of the procedure was performed using 20 representative target pesticides with an acetone extraction and a solid-phase extraction cleanup. These target pesticides were used to demonstrate repeatability and linearity of the chromatographic response and recovery from fruit and vegetable matrixes.     

超声液相萃取-GC/MS-SIM法定量检测唾液中苯丙胺类毒品

建立了一种人体唾液中苯丙胺(AM)、甲基苯丙胺(MAM)、 3, 4-亚甲二氧基苯丙胺(MDA)、 3, 4-亚甲二氧基甲基苯丙胺(MDMA)毒品的超声波液液萃取-气相色谱/质谱-选择离子检测方法. 对萃取溶剂、萃取时间等参数进行了考查, 确定了乙酸乙酯为萃取溶剂, 在超声波下液液萃取2 min. 用该溶剂对添加毒品的唾液进行提取, 采用气相色谱/质谱-选择离子检测法(GC/MS-SIM)检测, 获得了良好线性, 相对标准偏差在15%内, 准确性均在80%～115%之间, 最小检测限可达0.05 μg/mL. 该方法未对毒品进行衍生化处理, 可用于缴获毒品及嫌疑吸毒者人体生物检材中苯丙胺类毒品的分析.     

Determination of cefotaxime and desacetylcefotaxime in cerebrospinal fluid by solid-phase extraction and high-performance liquid chromatography

A microfluidic analytical system for the separation and detection of organic peroxides, based on a microchip capillary electrophoresis device with an integrated amperometric detector, was developed. The new microsystem relies on the reductive detection of both organic acid peroxides and hydroperoxides at -700 mV (vs. Ag wire/AgCl). Factors influencing the separation and detection processes were examined and optimized. The integrated microsystem offers rapid measurements (within 130 s) of these organic-peroxide compounds, down to micromolar levels. A highly stable response for repetitive injections (RSD 0.35-3.12%; n = 12) reflects the negligible electrode passivation. Such a "lab-on-a-chip" device should be attractive for on-site analysis of organic peroxides, as desired for environmental screening and industrial monitoring.     

Determination of remoxipride in plasma and urine by reversed-phase column liquid chromatography

A reversed-phase column liquid chromatographic method for the determination of remoxipride, a novel antipsychotic drug, in biological fluids is described. A simple one-step extraction is used followed by liquid chromatography on a 3-microns octadecylsilica column and ultraviolet absorbance detection. The method is accurate and precise for clinical remoxipride levels in both plasma and urine. For situations where a higher sensitivity is necessary a two-step extraction and a modified mobile phase are used. With this modification plasma concentrations down to 2 nM can be determined with acceptable precision.     

Determination of bovine butterfat triacylglycerols by reversed-phase liquid chromatography and gas chromatography

Triacylglycerols (TGs) from a sample of summer butterfat (bovine milk) were analysed and fractionated by reversed-phase liquid chromatography (RPLC). Fatty acid and TG composition of eac of the 47 RPLC fractions ranging from 0.1 to 6.9% were determined by capillary gas chromatography. The data were used together to determine the quantitative composition of the molecular species of TGs. A large number of TG species, accounting for 80% of the total, could be unequivocally identified and individually determined. The combination of the chromatographic methods used proved to be a powerful and accurate approach for the determination of molecular species of TGs in a complex fat, but also a difficult and time-consuming task.     

Determination of cis- and trans-1,3-dichloropropene in whole rat blood by gas chromatography and gas chromatography-chemical ionization mass spectrometry with selected ion monitoring

An analytical method was developed for quantitating low concentrations of the isomers cis- and trans-1,3-dichloropropene in whole rat blood by gas chromatography and gas chromatography-chemical ionization mass spectrometry with selected ion monitoring.     

Analysis of selected ionic liquid cations by ion exchange chromatography and reversed-phase high performance liquid chromatography

The chromatographic behavior of 8 ionic liquids - 7 homologues of 1-alkyl-3-methylimidazolium and 4-methyl-N-butylpyridinium - has been investigated with a strong cation exchange adsorbent. In particular, the dependence of the retention properties of these solutes on mobile phase composition, pH, and buffer concentration was evaluated with the aim of optimizing and improving the selectivity and retention of solute separation. While using the SCX stationary phase, several interactions occurred with varying strengths, depending on the mobile phase composition. Cation exchange, nonspecific hydrophobic interactions, and adsorption chromatography behavior were observed. Reversed phase chromatography occurred at low concentrations of acetonitrile, electrostatic and adsorption interactions at higher organic modifier concentrations. Elevated buffer concentrations lowered the retention factors without affecting the selectivity of ionic liquids. Obtained results were further compared to the chromatographic behaviour of ionic liquids in the reversed phase system. All analyzed ionic liquids follow reversed-phase behavior while being separated. Much lower selectivity in the range of highly hydrophilic compounds is obtained. This suggests preferred use of ion chromatography for separation and analysis of compounds below 4 carbon atoms in the alkyl side chain.     

Determination of pesticides in composite dietary samples by gas chromatography/mass spectrometry in the selected ion monitoring mode by using a temperature-programmable large volume injector with preseparation column.

Use of a temperature-programmable preseparation column in the gas chromatographic (GC) injection port permits determination of a wide range of semi-volatile pesticides including organochlorines, organophosphates, triazines, and anilines in fatty composite dietary samples while reducing sample preparation time and solvent consumption. Dietary samples are mixed with diatomaceous earth and are Soxhlet-extracted with an azeotropic solution of hexane and acetone. Sample preparation uses liquid-liquid partitioning over diatomaceous earth followed by normal phase chromatography over partially deactivated alumina. The final cleanup step occurs in a preseparation column in the GC injector, which is able to perform splitless transfer of the analytes to the analytical column and purge 99% of the high molecular weight residue. Detection is performed by GC/mass spectrometry (MS) in the selected ion monitoring mode. Method detection limits were at or below 2 ng/g for 24 of 35 pesticides studied, with recovery between 70 and 125% for 27 pesticides in samples fortified at 10 ng/g. Recovery was not dependent on fat content when measured in laboratory fortified samples containing 1, 5, and 10% fat by weight. Precision over multiple injections was acceptable, with a relative standard deviation of 2.6-15% for 25 analytes.     

反相硅胶整体柱离子色谱法快速分析BrO-3

研究了基于反相硅胶整体柱的离子色谱快速分析BrO;的方法.以氢氧化四丁铵(TBA)为流动相动态修饰反相硅胶整体柱,采用直接电导检测,在普通高效液相色谱仪上实现了BrO3-和常见阴离子的快速分析.实验考察并讨论了流动相、色谱柱温度和流速对所测阴离子保留和分离的影响.确定分离测定BrO3-的最佳色谱条件是:以0.75 mm...     

Determination of ceftriaxone in cerebrospinal fluid by ion-pair liquid chromatography

An ion-pair liquid chromatographic assay was developed and validated for the determination of ceftriaxone in cerebrospinal fluid. Chromatographic separation was achieved on a C18 column (125 x 4 mm, 5 microm) with detection at 270 nm, a 1 mL/min flow rate and a 50 microL loop. The mobile phase consisted of 300 mL acetonitrile, 50 mL 0.1M phosphate buffer (pH 7.4), 3.2 g tetrabutylammonium bromide as the ion-pairing agent, and dilution with distilled deionized water to 1 L. Cephradine was used as the internal standard. The assay was linear for ceftriaxone concentrations of 0.5-50 microg/mL. The coefficients of variation for precision were <4.61%. The accuracy ranged from 96.07 to 102.42%. The detection and quantitation limits were 0.019 and 0.065 microg/mL, respectively. This method was used to quantify ceftriaxone in the cerebrospinal fluid of children with meningitis. The results showed that the method described here is useful for the determination of ceftriaxone in cerebrospinal fluid.     

Determination of S-carboxymethylcysteine in serum by reversed-phase ion-pair liquid chromatography with column switching following pre-column derivatization with o-phthalaldehyde

A method is described for the determination of S-(carboxymethyl)-L-cysteine in serum. After addition of S-(carboxyethyl)-L-cysteine as internal standard, both compounds are extracted into methanol, converted into fluorescent derivatives with o-phthalaldehyde and quantitatively determined by reversed-phase high-performance liquid chromatography. Chromatography of unwanted amino acid derivatives is avoided by column switching, thereby shortening analysis time and increasing column lifetime. The technique was applied in a study of the bioavailability of S-(carboxymethyl)-L-cysteine after oral administration to humans. The concentration-response curve was linear from 2 to 16 micrograms/ml; mean serum concentrations are reported.