530μ大口径毛细管柱在气相色谱分析中的潜力

详细讨论了大口径毛细管柱的优点及其在许多常规分析中的应用以替代填充柱的可能性,列举出了在国内的一些成功的应用实例,还阐述了大口径柱的进样等技术和推广大口径柱存在的一些问题。     

Wide-bore glass capillary columns for gas chromatography. Their preparation and application

Summary Methods for the preparation of wide-bore glass capillary columns for gas chromatography are presented. The pretreatment of the columns (etching, carbonization, deactivation and/or surface-coating with porous materials), and the coating of them with polar or apolar phases (preferably by the static method) is described. The performance of the columns prepared is evaluated and a number of applications are given, such as analysis of volatile compounds, pesticides, lipids and GC/MS analysis. In some respects, the wide-bore glass capillaries have advantages over the narrow-bore types. They can be installed very easily in GC-instruments, and permit the analysis of larger samples. A system of collecting separated sub-g fractions in glass capillary traps, which makes direc re-injection from these traps possible, completes the methods presented.     

Some applications of capillary gas chromatography in the chemical industry

About three years ago, fused silica capillary columns were introduced in the Quality Control Laboratory of the Shell refinery/chemical complex at Pernis. In general, long, thick-film, wide-bore capillary columns are used together with low split ratios and hydrogen as carrier gas. These conditions enable the analysis of relatively large sample amounts, resulting in low detection limits for the minor components without overloading by the major components, while still maintaining a satisfactory resolution. A number of applications are shown, such as the analysis of complex mixtures, the determination of trace impurities and the analysis of residual volatiles in polymers.     

Determination of 4-aminobutyric acid, aspartate, glutamate and glutamine and their 13C stable-isotopic enrichment in brain tissue by gas chromatography-mass spectrometry

A selected-ion monitoring method was developed for measuring 4-aminobutyric acid, aspartate, glutamate, and glutamine in brain tissue. Natural isotopes of these amino acids and their stable-isotopic enrichment following intravenous infusion of a precursor, [13C]glucose, were quantitated. Frozen mouse brain tissue was homogenized in cold 80% ethanol, and the supernatant, equivalent to 1 mg of wet weight brain tissue, was extracted using solid-phase bonded silica ion-exchange columns. Aspartate and glutamate (dicarboxylic acids) were isolated from strong anion-exchange columns, whereas 4-aminobutyric acid and glutamine (neutral amino acids) were isolated from strong-cation exchange columns. n-Butyl ester pentafluoropropionyl amide derivatives of these amino acids were analyzed by gas chromatography-mass spectrometry using a methane positive chemical ionization mode after gas chromatographic separation on a wide-bore, fused-silica capillary column. The method is applicable to determination of brain concentrations of these amino acids as well as their fluxes following administration of a stable-isotopic tracer.     

窄内径多孔层开管柱的制备及在液相色谱中的应用

近年来,微纳分离技术由于其内在的优势而受到越来越多的关注.多孔层开管柱是一种重要的微分离柱形式,与粗内径的多孔层开管柱(>25μm)相比,窄内径的多孔层开管柱具有更高的分离效率和更低的试剂消耗量.本文综述了内径≤25μm的窄内径多孔层开管毛细管柱的制备方法、与质谱检测联用技术以及在液相色谱中的应用研究进展,对其发展前景进行了展望.     

Interface for coupling nonaqueous wide-bore capillary electrophoresis with mass spectrometry

A liquid-junction-type interface where a thin spraying capillary is inserted inside the separation capillary was constructed for coupling nonaqueous wide-bore capillary electrophoresis (CE) to mass spectrometry (MS). The robust structure of the interface provided fairly easy capillary handling. The study was carried out with uncoated CE capillaries of 200 and 320 microm inner diameter (ID). 1-Propanol-acetonitrile (80:20 v/v) with acetate electrolyte provided a low conducting medium for CE and good spraying conditions for electrospray ionization (ESI) without sheath-flow and drying gas. Methamphetamine, alprenolol, and levorphanol served as model compounds. Approximate detection limits with the 200 microm ID capillary were 35-265 ng/mL.     

Arsenic speciation by capillary gas-liquid chromatography

Specific environmentally significant arsenic compounds are determined by capillary gas-liquid chromatography. Inorganic (arsenite, arsenate) and organic (monomethylarsonate, dimethylarsinate) arsenicals are measured as the corresponding methylthioglycolate derivatives, which are simultaneously separated on wide-bore borosilicate glass and fused-silica columns under conditions of temperature programming. Inorganic arsenate and arsenite cannot be differentiated by the derivatization technique. Flame-ionization and electron-capture detection are evaluated. A simple and rapid sample preparation procedure is used for water, urine, blood, and tissue.     

Drug matrix effect on the determination of residual solvents in bulk pharmaceuticals by wide-bore capillary gas chromatography.

A wide-bore capillary gas chromatographic method has been developed to study the drug matrix effect on the determination of residual solvents in bulk pharmaceuticals. A selective method is achieved on a Restek wide-bore (0.53-mm i.d. x 30 m) open-tubular fused-silica column coated with a 5-micron film of 95% dimethyl-5% diphenyl polysiloxane protected by a phenyl-methyl siloxane deactivated, uncoated fused-silica guard column. Utilizing this method, several common process solvents in weakly acidic, weakly basic, and neutral drug matrices are evaluated by recovery and linearity studies to show whether or not a drug matrix effect exists in their determination.     

Steroid analysis by gas chromatography with SCOT and wide-bore WCOT columns

Glass capillary columns are ideal for analysis of urinary steroid profiles (i.e. the total steroid neutral fraction without prior separation into sub-groups). In this paper performance of both SCOT and wide-bore WCOT columns has been compared, resulting in no significant quantitative difference on urine extracts run as trimethylsilyl ether derivatives. However, because of increased efficiency the WB-WCOT column exhibited more sensitivity in measurement of small amounts of 11-ox-aetiocholanolone. Sensitivity of other steroids was greatly enhanced by use of either SCOT or WB-WCOT, leading to an almost tenfold increase over conventional packed columns (e.g. androsterone and aetiocholanolone < 40 μg per 24 h urine sample). A simple splitless injection system (based on a design of Dr. W. Greenaway, Oxford University) is presented. Experiments were also carried out using a SCOT column in conjunction with an FM-electron capture detector. Whilst efficiency was impaired due to the design of the detector, use of He (carrier) and N₂ (make up gas) showed that several steroid derivatives could be easily measured at well below the 10^?10 g level with much more rapid retention times than with a 1½m packed column. Highly successful separation of 19 amino acids (as fluoro-acyl derivatives) was achieved in 35 minutes using a SCOT (30 m) SP2100 column.     

气相色谱法直接测定植物生长素

 建立了一种采用 5 3 0 μm大口径毛细管色谱柱、不经衍生化处理而直接测定吲哚乙酸 (IAA)、吲哚丁酸(IBA)和萘乙酸 (NAA)等植物生长素的气相色谱分析方法。以邻苯二甲酸二丁酯为内标物 ,用 FID检测 ,IAA,IBA和 NAA的相对标准偏差分别为 1 .1 4% ,0 .61 %和 0 .78%。方法简便、快速、准确、重现性好 ,可用于生长素类单组分和混合制剂的质量检测。     

毛细管气相色谱法测定腈纶布料中苯、甲苯和二甲基甲酰胺残留

 建立了同时定量测定腈纶布料及其服装中的苯、甲苯和二甲基甲酰胺残留的毛细管气相色谱分析方法。测得的回收率分别为 93 .3 % ,1 0 1 .8% ,94.9% ;变异系数为 3 .4% ,2 .0 % ,2 .8%。方法简便、快速、准确。     

Evaluation of gas chromatographic columns for the determination of methylmercury in aqueous head space extracts from biological samples.

Several gas chromatographic columns were evaluated for the determination of methylmercury in aqueous solution. The goal of the study was to further decrease the detection limit of the recently developed method of head space gas chromatography with microwave-induced plasma detection (HS-GC-MIP) for the determination of methylmercury in biological samples. The columns were first evaluated using gas chromatography with electron-capture detection (ECD). At the same time, the column efficiencies for the determination of ethyl- and phenylmercury were also studied. Of the packed columns the stationary phase used previously in HS-GC-MIP, AT-1000, yielded the best results. Better results were obtained with two wide-bore thick-film fused-silica open tubular (FSOT) columns, one of which was suitable for aqueous injections (Superox-FA) and the other for benzene or toluene (RSL-300). With these FSOT columns, absolute detection limits at the sub-picogram level were reached. A new HS-GC-MIP system was then constructed, which was adapted for the use of FSOT columns. As more sensitive measurements were obtained with a Superox-FA FSOT column than with an AT-1000 packed column using the GC-ECD system in the first part of this study, the FSOT column was evaluated in this HS-GC-MIP system for the determination of methylmercury in real tissue samples. It was demonstrated that the use of an FSOT column gives only a small decrease in the detection limit compared with a packed column; reconditioning of the FSOT column is, however, a disadvantage in routine measurements.     

Permeability, porosity, and structure of monolithic capillary columns in gas chromatography

The permeability of monolithic silica gel capillary columns with respect to the helium carrier gas was studied using gas chromatography. The results obtained by gas chromatography and liquid chromatography were found to be in close agreement. The permeability of monolithic capillary columns was compared to that of hollow capillary columns and columns packed with finely dispersed sorbents. It was demonstrated that the permeability of the monolithic capillary columns studied is almost three orders of magnitude lower than that of hollow capillary columns of the same diameter but two orders of magnitude higher than that of columns packed with micron-scale particles. The interstitial fraction of the monolithic columns was found to be very high, 0.95.     

Evaluation of fused-silica capillary columns for GC/ECD analysis of chlorinated hydrocarbons listed in EPA method 8120

Four mega-bore, one wide-bore, and one narrow-bore fused-silica capillary columns were evaluated for their applicability to the GC/ECD analysis of 22 chlorinated hydrocarbons, some of which are currently targeted by EPA Method 8120. No one column can resolve all 22 compounds investigated here. Four compounds (two pairs) are coeluting on the SPB-35, DB-210, DB-WAX, and DB-519 fused-silica capillary columns, five compounds (two groups) are coeluting on the DB-1301 fused-silica capillary column, and ten compounds (five pairs) are coeluting on the SPB-5 fused-silica capillary column. The analysis time varies between 30 and 50 min. The order of elution of the chlorinated benzenes seems to depend on their boiling points rather than on the polarity of the liquid phase. The retention times of an additional nine chlorinated toluenes, eight chlorinated xylenes, and five chlorinated naphthalenes are also reported. Electron capture detector linearity is reported for the DB-210 fused-silica capillary column. Five brominated compounds were investigated as possible internal standards for Method 8120.     

Determination of clozapine in human serum by capillary gas chromatography

A gas chromatographic method using a fused-silica wide-bore capillary column and a nitrogen-specific detector for the determination of the antipsychotic agent clozapine in human serum is described. This method was found to be suitable for the determination of serum levels down to 1-2 ng/ml. The sensitivity, precision and accuracy of this method are adequate for studies on pharmacokinetics and bioavailability.     

Determination of methanol in whole blood by capillary gas chromatography with direct on-column injection.

A gas chromatographic procedure was developed for the determination of methanol in small-volume whole blood samples. Samples (100-200 microliters) were prepared by protein precipitation, with direct injection of the supernatant on a wide-bore capillary column. The recovery of methanol and acetonitrile (the internal standard) was approximately 90% and did not vary with sample volume. The assay was linear from 2 micrograms/ml (the limit of detection) through 1000 micrograms/ml and was highly reproducible (intra-day coefficient of variation less than 2.5%). Assay performance was assessed following exposure of rats to methanol. The results indicate that the present procedure is suitable for studies of methanol disposition in small rodent species.     

毛细管气相色谱法同时测定鸡蛋中的胆固醇和α-维生素E

 采用 2 0mol/L的KOH乙醇溶液直接皂化 ,石油醚萃取 ,大口径毛细管气相色谱法测定鸡蛋中的胆固醇和α 维生素E(α VE) ,讨论并确定了鸡蛋样品皂化的最佳条件。胆固醇和α VE的回收率分别为 91.0 %～ 93.3%和82 .5 %～ 95 .0 % ,其RSD分别为 2 7%～ 3 1%和 4 9%～ 6 9% (n =5 )。该法具有简便、快速、灵敏、准确等优点。     

Indirect fluorescence detection in capillary gas chromatography

Post-column addition of naphthalene vapour to the effluent from a wide-bore capillary gas chromatographic column, prior to gas-phase fluorescence detection, was used to detect fluorescent and non-fluorescent species as positive and negative peaks, respectively. Quenching constants were determined for nitrobenzene and cyclohexanone using indirect detection.     

The Influence of the Natures of the Carrier Gas and the Stationary Phase on the Separating Properties of Monolithic Capillary Columns in Gas Adsorption Chromatography

A model mixture of light hydrocarbons was used to study the separation capacity of monolithic capillary columns based on divinylbenzene with five different carrier gases, including helium, hydrogen, nitrogen, carbon dioxide, and nitrous oxide. The results were correlated with the previously obtained data on monolithic columns based on silica gel. It was shown that the influence of the nature of the carrier gas was weaker than for silica gel columns; the polymeric columns studied behaved similarly to hollow capillary columns with polymeric stationary phases and exhibited an efficiency gain of 20–30% along the series He < H₂ < N₂ ～ N₂O < CO₂. Based on the minimum HETP (～15 μm) obtained for the investigated monolithic columns under optimum conditions with N₂O or CO₂ as a carrier gas, the conclusion was drawn that the creation of divinylbenzene-based monolithic capillary columns with a high specific efficiency was possible.     

Performance of open tubular columns as a function of tube diameter and liquid phase film thickness

Summary Wall-coated, open-tubular (capillary) columns prepared from different diameter tubing, with different liquid phase film thickness, are compared with each other and with packed and support-coated open-tubular columns. The comparison is based on the variation of the phase ratio and the capacity factor, and includes column efficiency (HETP, theoretical plate number), resolution, retention time, and sample capacity. Problems associated with the evaluation of the sample capacity are outlined. The influence of temperature on column performance is discussed in detail. Finally, the possibilities of short, wide-bore open-tubular columns prepared with a thick liquid-phase film are demonstrated.Parts of this paper were presented at the 35th Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Atlantic City NJ, March 5–9, 1984, and at the 20th International Symposium on Advances in Chromatography, New York NY, April 16–18, 1984.