固相萃取结合超高效液相色谱-串联质谱法及气相色谱-负化学源质谱法测定人血清中的四溴双酚A、六溴环十二烷和多溴联苯醚

建立了固相萃取同时提取、净化血清中四溴双酚A(TBBPA)、α, β, γ-六溴环十二烷(HBCD)和8种多溴联苯醚(PBDEs)同系物的样本前处理方法,并结合色谱-质谱分离分析技术检测人血清样本中该类化合物的含量。试样在加入各自的同位素内标物后以甲基叔丁基醚/正己烷(1:1, v/v)混合溶剂进行萃取,再经浓硫酸去除脂肪后,以LC-Si固相萃取柱分离HBCD/TBBPA和PBDEs。采用分步检测的方式,在50 mm长BEH C18反相色谱柱上以超高效液相色谱-串联质谱(UPLC-MS/MS)的多反应监测模式(MRM)检测HBCD和TBBPA,在15 m长的毛细管柱上以气相色谱-负化学源质谱(GC-NCI/MS)的选择离子监测模式(SIM)检测PBDEs。以胎牛血清为空白基质,当HBCD、TBBPA和BDE-209的加标水平为0.5 ng/g和5 ng/g、三溴至七溴联苯醚的加标水平为0.05 ng/g和0.5 ng/g时,它们的平均加标回收率为80.3%～108.8%,相对标准偏差为1.02%～11.42%(n=5);以信噪比(S/N)为3计算,方法的检出限(LOD)为1.81～42.16 pg/g。采用该方法对实际样品进行测定,结果表明,本方法快速、准确、灵敏度高,能够满足血清中HBCD、TBBPA和PBDEs残留的同时提取及测定的要求。     

Fast analysis by gas-liquid chromatography. Perspective on the resolution of complex fatty acid compositions

Separation of fatty acids as methyl ester (FAME) derivatives has been carried out using short and highly polar capillary column developed for fast gas-liquid chromatography (GLC) applications. The GLC parameters have been optimized in order to achieve separation of FAME ranging from 4:0 (butyric acid) to 24:1 in less than 5 min. Milk fat that has by far the most complex fatty acid composition among edible fats and oils has been used to optimize the method. The volume of the oven has been reduced in order to allow for a heating rate of 120 degrees C/min and to rapidly cool-down to the initial temperature (50 degrees C) of the GLC program. The GLC conditions developed are not suitable to achieve separation of positional and geometrical isomers of octadecenoic acid but are useful to perform separation of major fatty acids in milk fat. The conditions developed could be used to analyze edible fats and oils or biological samples such as plasma or red blood cell lipids. The results confirmed that short and highly polar fast columns operating under optimal conditions could be used to separate the fatty acids in various matrices.     

Assessment of serum cholesterol by two methods: gas-liquid chromatography on a capillary column and chemical ionization-mass fragmentography with isotopic dilution of [3,4-13C] cholesterol as internal standard.

A gas-liquid chromatographic (GLC) method and an isotopic dilution-mass fragmentographic (ID-MF) procedure using the same capillary chromatographic separation are described for serum cholesterol assay. GLC included silylation and separation on a highly efficient glass capillary column which allowed the separation of cholesterol from cholestanol and the use of epicoprostanol as internal standard. The concentrations were calculated from the areas of the signals and digitalized by a reporting integrator. The reproducibility was 0.5% and the correlation with the ID-MF technique was 0.997. The ID-MF technique was characterized by the use of [3,4-13C] cholesterol as the labelled standard and a chemical ionization mode. The reproducibility was 0.8%.     

Characterization of a lipid-rich fraction synthesized by Streptomyces avermitilis

Isolation of the macrocyclic lactone parasiticide avermectin and other closely related natural products produced by Streptomyces avermitilis also yields a lipid-rich fraction. The latter has been characterized by techniques based on gas-liquid chromatography (GLC) and mass spectrometry (MS). Initial examination of the lipid-rich fraction by direct probe electron-impact (EI) MS and packed-column GLC showed that it consists primarily of a mixture of triglycerides possessing C14-C17 acyl groups. Further examination of this fraction by capillary column GLC-MS demonstrated that it contains low levels of C15-C17 free fatty acids, squalene and diglycerides and, as the major components, at least ten mixed acyl triglycerides (total number of acyl carbon atoms ranging from 43 to 50). Prominent among the triglycerides were a C15-C15-C16 species, a C15-C16-C16 species and a C15-C16-C17 species. Capillary-column GLC and GLC-MS of the fatty acid methyl esters resulting from transesterification demonstrated that the major triglyceride acyl groups are anteiso-C15 (12-methyltetradecanoyl), iso-C16 (14-methylpentadecanoyl), n-C16 (hexa-decanoyl) and anteiso-C17 (14-methylhexadecanoyl). Lower levels of the methyl esters of the following fatty acids were observed: iso-C14 (12-methyltridecanoic), n-C14 (tetradecanoic), iso-C15 (13-methyltetradecanoic), n-C15 (pentadecanoic), iso-C17 (15-methylhexadecanoic) and n-C17 (heptadecanoic). Little evidence was seen for either unsaturated acyl groups or acyl groups of less than 13 or more than 18 carbon atoms. Desorption chemical ionization MS (ammonia reagent gas) analysis confirmed the nature of the lipid-rich fraction, and is an attractive one-step approach for determining the molecular weights and distribution of triglycerides in a mixture.     

C_5馏分及其羰化产物的毛细管气相色谱分析

石油裂解副产物C5馏分及其羰化产物是成分较为复杂的混合物,尤其是C5馏分中1,3-环戊二烯和顺-1,3-戊二烯的物性更为接近。用SE－54弹性石英毛细管柱和角鲨烷玻璃毛细管柱分别对C5馏分及其羰化产物进行了分析,使各组分达到了很好的分离。     

Analytical methodology to determine stable isotopically labelled and unlabelled theophylline in human plasma using capillary gas chromatography-mass spectrometry

A method is described for the simultaneous determination of [1,3-15N] theophylline and unlabelled theophylline in human plasma using gas chromatography-mass spectrometry. Plasma samples were subjected to extractive alkylation and the stable isotopically labelled and unlabelled forms of the drug were analysed as their N-pentafluorobenzyl derivatives on an SE-52 fused-silica capillary column. Quantitation was made by selected-ion monitoring employing as the internal standard 3-isobutyl-1-methylxanthine. The method has been used to study the absorption kinetics and bioavailability of a sustained release formulation of the drug when co-administered to human volunteers with a conventional formulation of the drug labelled with the stable isotope.     

Gas chromatographic characteristics and application studies of the stationary phase of CH-B-15-C-5

In this paper, separations of organic compounds, such as, n-alkanes, alcohols, ethyl asters of C(1)-C(8) carboxylic acid, halogen derivatives, position-isomers of the replacement aromatic hydrocarbon, optical isomers of ethyl lactate and isoamyl alcohol, etc. were studied using 4'-cholestenoxycarbonyl-benzo-15-crown-5 liquid crystal crown ether (CH-B-15-C-5) as stationary phase in gas-solid chromatography (GSC), general gas-liquid chromatography (GLC) and crown ether liquid crystal gas-liquid chromatography (CL-GLC). Also, the chromatographic characteristics, such as the chemical stability, thermal stability, selectivity, polarity and operating temperature range, of the CH-B-15-C-5 as stationary phase for GSC, GLC and CL-GLC systems were studied. The results showed that the polarity of this chromatographic column is mean-weak; the chemical and thermal stabilities and the selectivity are good and the operating temperature range is wide. The results of separations of organic compounds are satisfactory.     

A gram scale synthesis of a multi-13C-labelled anthocyanin, [6,8,10,3',5'-13C5]cyanidin-3-glucoside, for use in oral tracer studies in humans

The major dietary anthocyanin, cyanidin-3-glucoside, was prepared on a 4 g scale from three units of diethyl [2-(13)C]malonate and one unit of [1,3-(13)C(2)]acetone, such that five isotope locations were distributed throughout the molecule to provide a penta-(13)C(5)-labelled anthocyanin, [6,8,10,3',5'-(13)C(5)]cyanidin-3-glucoside chloride, for use in human stable-isotope tracer studies.     

Gas chromatographic assay with pharmacokinetic applications for monitoring T-2 and HT-2 toxins in plasma

A gas-liquid chromatographic (GLC) method for monitoring T-2 and HT-2 toxins in plasma was developed. The procedure involved extraction of the toxins with ethyl acetate, chromatography on a C18 reversed-phase column and derivatization with heptafluorobutyric anhydride (HFBA). The T-2 and HT-2 HFBA derivatives were chromatographed on OV-17 at various temperatures and measured with an electron-capture detector. Iso-T-2 toxin and iso-HT-2 toxin were used as internal standards. Recoveries averaged 95.1 +/- 8.6% for T-2 toxin and 102.1 +/- 5.2% for HT-2 toxin at levels ranging from 40 to 120 ng/ml. The limits of detection were 30 and 5 ng/ml of T-2 and HT-2 toxin, respectively. The range of the assay covers plasma concentrations at which toxicity becomes manifest. The pharmacokinetic application of this GLC method is illustrated by simultaneous monitoring of T-2 and HT-2 toxins levels in plasma obtained after intravenous administration of T-2 toxin to a dog.     

Solubilities of volatile solutes in poly(vinyl acetate) from 125 to 200°C

Gas-liquid chromatography (GLC) was used to measure Henry's law constants for ethylene, ethane, carbon dioxide, sulfur dioxide, methyl chloride, vinyl acetate, isopropyl alcohol, methyl ethyl ketone, and acetone in liquid poly(vinyl acetate) in the region 125 to 200°C. Retention-time differences were measured relative to nitrogen and corrections for nitrogen's finite solubility were applied; these corrections are significant when measuring the solubilities of sparingly soluble solutes by the GLC method. The effect of GLC column diameter is discussed.     

Enantioselective determination of felodipine and other chiral dihydropyridine calcium entry blockers in human plasma

A sensitive method for the enantioselective determination of felodipine in human plasma is described. Following alkaline extraction with dichloromethane-pentane, racemic felodipine and its primary pyridine metabolite are simultaneously assayed using capillary gas chromatography on a DB-1 column, with electron-capture detection. The enantiomers of felodipine are quantitatively separated by high-performance liquid chromatography on a Chiralcel OJ column, containing tris(4-methylbenzoate)-modified cellulose coated on silica, and off-line detection using the same gas chromatographic system is applied. The limits of determination in plasma (and the inter-assay coefficient of variation (C.V.) at levels below 1 ng/ml) were 0.1 ng/ml (C.V. 13%) for felodipine, 0.1 ng/ml (C.V. 15%) for the enantiomers of felodipine and 0.3 ng/ml (C.V. 7%) for its pyridine metabolite. The method has proved to be applicable to several other chiral dihydropyridine calcium entry blockers, including nitrendipine, with comparable sensitivities.     

Micro-scale analysis of aminoglycoside antibiotics in human plasma by capillary liquid chromatography and nanospray tandem mass spectrometry with column switching

A simple liquid chromatographic method combined with tandem mass spectrometry (LC-MS-MS) is described for the analysis of aminoglycoside antibiotics. Clinically these antibiotics may cause both ototoxicity and nephrotoxicity; therefore, the monitoring of aminoglycoside levels in patient plasma is required for protecting human health. In this study separation of the method is based on ion-pair chromatographic technology on a short capillary reversed-phase C18 column. The method was successfully applied to analyze amikacin in human plasma. In human plasma after deproteinisation with HFBA, an aliquot of 1 microL supernatant was injected into the chromatographic system. Only a small amount of plasma sample, 10 microL, is sufficient for the monitoring of amikacin levels in clinically therapeutic range. The relative standard deviations (RSD) of the method for intra- and inter-day analyses (n=5) are less than 5.8%. Application of this method for the trace analysis of amikacin in human plasma proved simple and workable.     

用毛细管色谱法分析14种拟除虫菊酯立体异构体

用石英毛细管柱分离了14种拟菊酯的立体异构体。柱1用QF-1固定液10m×0.53mm×1.0μm膜厚,柱温在180℃～260℃之间,可完全分离右旋丙炔菊酯等10种拟菊酯的立体异构体。往2为HP-525m×0.53mm×1.0μm膜厚,用合适的住温可分离百治菊酯等4种拟菊酯的异构体。     

How to utilize the true performance of monolithic silica columns

Ways of utilizing the true separation efficiency of monolithic silica (MS) columns were studied. The true performance of MS columns, both regular-sized (rod-type clad with PEEK resin, 4.6 mm ID, 10 cm) and capillary sized (in 100 or 200 microm ID fused silica capillary, 25-140 cm) was evaluated by calculating the contribution of extra-column effects. HETP values of 7-9 microm were observed for solutes having retention factors (kvalues) of up to 4 for rod columns and up to 15 for a capillary column. The high permeability of MS columns allowed the use of long columns, with several connected together in the case of rod columns. Narrow-bore connectors gave good results. Peak variance caused by a column connector ranges from 50 to 70% of that caused by one rod-type column for up to three connectors or four columns in 80% methanol, but the addition of a 4th or 5th connector to add a 5th and 6th column, respectively, caused a much greater increase in peak variance, especially for long-retained solutes, which is greater than the variance caused by one rod column. Rod columns seem to show slightly lower efficiency at a pressure higher than 10 MPa or so. The use of acetonitrile-water as a mobile phase better preserved the ability of individual rod columns to generate up to 100,000 theoretical plates with 14 columns connected. Methods for eliminating extra-column effects in micro-HPLC were also studied. Split injection and on-column detection resulted in optimum performance. A long MS capillary measuring 140 cm produced 160,000 theoretical plates. The column efficiency of a capillary column was not affected by the pressure, showing advantages over the rod columns that exhibited peak broadening caused by connectors and pressure.     

Simultaneous determination of stable isotopically labelled L-histidine and urocanic acid in human plasma by stable isotope dilution mass spectrometry.

A capillary gas chromatographic-mass spectrometric method for the simultaneous determination of stable isotopically labelled L-histidine (L-[3,3-2H2,1',3'-15N2]histidine, L-His-[M + 4]) and urocanic acid ([3-2H,1',3'-15N2]urocanic acid, UA-[M + 3]) in human plasma was developed using DL-[2,3,3,5'-2H4,2'-13C,1',3'-15N2]histidine (DL-His-[M + 7]) and [2,3,5'-2H3,2'-13C,1',3'-15N2]urocanic acid (UA-[M + 6]) as internal standards. L-Histidine and urocanic acid were derivatized to alpha N-(trifluoroacetyl)-imN-(ethoxycarbonyl)-L-histidine n-butyl ester and imN-(ethoxycarbonyl)urocanic acid n-butyl ester. Quantification was carried out by selected ion monitoring of the molecular ions of the respective derivatives of L-His-[M + 4], DL-His-[M + 7], UA-[M + 3] and UA-[M + 6]. The sensitivity, specificity, precision and accuracy of the method were demonstrated to be satisfactory for measuring plasma concentrations of L-His-[M + 4] and UA-[M + 3] following administration of trace amounts of L-His-[M + 4] to humans.     

Determination of the GABAergic antidepressant drug fengabine and some of its metabolites in plasma by capillary gas chromatography with electron-capture detection

A sensitive capillary gas chromatographic method was developed for the determination of fengabine (a GABAergic antidepressant drug) and some of its metabolites in plasma samples. The method involves a single and rapid liquid-liquid extraction of the parent drug and metabolites from plasma buffered at pH 5, evaporation of the organic phase under nitrogen, derivatization to tert.-butyldimethylsilyl ethers and esters and automatic gas chromatography on a fused-silica, silicone-bonded capillary column coupled to an electron-capture detector. The detection limit for fengabine and other compounds is lower than 1 ng/ml in plasma; the method was successfully applied to pharmacokinetic and drug monitoring clinical studies and tested on more than 2000 biological samples and was found not to suffer from endogenous or exogenous interferences.     

Rapid Chromatography for the Determination of Polychlorinated Biphenyls by GC-MS in Environmental Monitoring

A method for determination of polychlorinated biphenyls (PCBs) in environmental and biological materials has been developed. This method includes rapid chromatography requiring less than 10 min using an HT-8 capillary column at 30 m × 0.25 mm i.d. Rapid chromatography was performed using a column temperature gradient from 80 to 310°C at a rate of 40°C/min. Low-resolution mass spectrometry in single ion monitoring mode of simultaneous detection of 12 target ions is suggested for detection of PCBs peaks. The method not only enabled us to reduce time of analysis but also to increase the efficiency of separating PCB peaks from interferences and to reduce levels of detection of analytes resulting in a minimized sample preparation stage. The last includes extraction of the PCBs using organic solvents, preliminary alkaline hydrolysis in the case of biological objects, and cleaning up the extracts on compact cartridges. The method was tested in monitoring studies for these contaminants in soils, sediments, snow cover, fish tissues, and seal blubber. Total PCBs and isomer congener groups of the same chlorination degree and seven indicator congeners (IUPAC No.'s 28, 52, 101, 118, 138, 153, and 180) are determined with a high degree of certainty. The PCB concentrations were in the range of 1–700 ng/g dry weight for environmental samples and 500–25000 ng/g lipids for biota. The method yields measurements of total PCBs and isomer groups with a precision no greater than 10% and no greater than 15% for the indicator congeners.     

Determination of the enantiomeric purity of 2-(2′-carboxy-3′-phenylcyclopropyl)glycines by chiral capillary electrophoresis

Summary A fast and practical chiral capillary electrophoretic method has been developed for determination of the enantiomeric purity of 2-(2′-carboxy-3′-phenylcyclopropyl)glycine (PCCG) compounds. In particular, the isomer PCCG-13, a potent selective and competitive antagonist at phospholipaseD-coupled metabotropic glutamate receptors (mGluRs), was completely resolved from its enantiomer PCCG-15 by use of dimethyl-β-cyclodextrin (DMCD) as chiral selector. pH 9.0 running buffer containing 2-amino-2-methyl-1,3-propanediol (AMPD; 100mM) was a suitable medium enabling resolution of the enantiomers in a short (32.5 cm total length) poly(vinyl alcohol) (PVA)-coated capillary. Because of the suppression of the electroosmotic flow and the good peak shape, baseline resolution of the enantiomers was obtained by use of the optimum concentration of chiral selector. For quantitative purposes at impurity levels, high sample loading was required and adequate separation was obtained in the presence of 80 mM DMCD. This CE method enabled quantification of 0.3% m/m of undesired enantiomer in PCCG-13; the samples analyzed, obtained from enantioselective synthesis, proved to be of high enantiomeric purity.     

Multiresidue determination of chlorophenoxy acid herbicides in human urine samples by use of solid-phase extraction and capillary LC–UV detection

Chlorophenoxy acid herbicides are intensively applied to get rid of unwanted plants because of their low cost and selectivity. Due to their toxicity, which depends on their chemical form, the European Community has established legal directives to restrict their use and to control their maximum residue levels in several matrices. Determination of chlorophenoxy acids—2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-2-methylphenoxyacetic acid (MCPA), 2-(2,4-dichlorophenoxy)propanoic acid (2,4-DP), 2-(4-chloro-2-methylphenoxy)propanoic acid (MCPP), 4-(4-chloro-2-methylphenoxy)butanoic acid (MCPB) and 2-(2,4,5-trichlorophenoxy)propanoic acid (2,4,5-TP) in spiked human urine samples has been carried out by capillary LC, after solid-phase extraction on a column packed with silica C₁₈ restricted-access material. Chromatographic analysis was performed in gradient-elution mode at 25 °C, with injection of 20 μL low-organic-solvent composition herbicide solutions for focusing purposes on the head of the capillary column, and diode array detection at 232 nm. Urine samples collected during 24 h from healthy and unexposed volunteers were spiked in the concentration range 25–150 μg L⁻¹; recoveries obtained were between 66 and 100% (n = 6 for each spiked level) and RSDs (relative standard deviations) were between 1 and 5%. Detection limits in the urine samples from volunteers were between 3.5 and 6.0 μg L⁻¹. The developed methodology has allowed the clean-up and preconcentration of low volumes of untreated human urine without previous treatment, showing the effectiveness of the employed SPE sorbent for extracting the target analytes and ultimately resulting in the reduction of the sample-preparation time.