Ultra-fast essential oil characterization by capillary GC on a 50 microm ID column

A 5 m x 50 microm capillary column with 0.05 microm stationary phase film thickness, with a calculated efficiency of almost 20,000 plates per metre (under optimum conditions), was used for very fasthigh resolution GC analysis of lime essential oil. The total analysis time of this volatile essential oil was less than 90 s. Fast GC is shown to be appropriate for essential oil quality assurance analysis, and quantitative results of key components are comparable with those obtained by using conventional GC analysis. The fast GC analysis is approximately 33 times faster than the conventional GC method.     

Sample-stacking techniques in non-aqueous capillary electrophoresis

In sample-stacking techniques, the detection limit cannot be improved by simply increasing the length of the sample solution, because the individual electrophoretic parameters must be optimized. In an attempt to increase the amount of sample injected, as well as to focus them onto a small zone, two novel methods are proposed. One of these employs an "ultra-high conductivity zone", which was inserted between the sample zone and background solution to build an unequal conductivity gradient. The other employs a "low temperature bath". A portion of the capillary (near the junction between the sample solution and the background solution) was immersed in a low temperature bath, which served as a "pseudo-high-conductivity zone" due to the fact that conductivity would increases when the temperature is decreased. As a result, a large volume of sample injection can be achieved. Using 3,4-methylenedioxymethamphetamine as a model compound, the detection limit was determined to be 1.6 x 10(-6) M (S/N = 3) by means of normal non-aqueous capillary electrophoresis (NACE). This could be improved to 3.0 x 10(-8) M, 4.8 x 10(-9) M and 5.0 x 10(-9) M, respectively, when the normal stacking, ultra-high conductivity zone NACE-stacking and the low-temperature zone NACE-stacking methods were applied.     

Fused silica capillary micro-packed columns in gas chromatography

Summary Flexibility, strength and adsorption inertness of fused-silica capillaries permits their extensive application for the preparation of micro-packed columns in gas chromatography. Decreasing the column diameter (from 0.5 to 0.15 mm) and the diameter of the sorbent particles (from 100 to 5 μm) results in a marked reduction of the height equivalent to a theoretical plate (HETP), as well as in diminishing the dependence of the HETP on the carrier gas flow rate. The chromatographic characteristics of fused-silica capillary micro-packed columns and open-tubular columns are compared. The fused-silica capillary micro-packed column can be used to advantage for performing rapid and trace analyses and have been shown to be adapted for application in gas-solid chromatography. Separation of organic and inorganic compounds on fused-silica capillary micro-packed columns is illustrated by practical examples. Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984     

Determination of imazalil by on-line coupled capillary isotachophoresis with capillary zone electrophoresis

A simple, rapid and reproducible capillary isotachophoretic on-line coupled with capillary zone electrophoresis (CITP-CZE) method for the determination of IMz in food packaging extracts and its residues in apples is described. A good separation of the IMZ from other sample constituents was achieved within 15 minutes without any sample clean up. Method characteristics (linearity, accuracy, intra-assay and detection limit) were determined. Less amount of time involved, sufficient sensitivity and low running cost are the important attributes of CITP-CZE method.     

Surface modification of soft-glass capillaries for gas chromatography by treatment with water vapour

“Leaching” or “etching” by strong mineral acids seems to be a necessary pretreatment step for the most commonly used deactivation procedures of glass capillaries by reaction with either polyethylene glycol or silylation reagents. The acidic sites which are formed on the surface during this acid treatment cannot be completely removed by the subsequent deactivation process. This drawback can be overcome by performing the leaching with water vapour, resulting in an accumulation of cations at the surface and a decrease in the number of silanol groups. Capillaries of this type show excellent properties for the chromatography of strongly basic compounds. After the wash-out of the alkaline surface layer, the acidity of the support is suited for the chromatography of strongly basic as well as strongly acidic compounds. Due to a lack of reactive acidic sites, special deactivation procedures have to be applied to capillaries produced in this way.     

Direct analysis of alkylnaphthalenes in crude oils by two-dimensional capillary gas chromatography

Summary Diaromatics are geochemically significant constituents of crude oils. Their determination is usually achieved by elaborate prefractionation methods, such as medium pressure liquid chromatography and HPLC, prior to capillary gas chromatography. The present contribution describes the quantitative analysis of methylnaphthalenes, ethylnaphthalenes, and dimethylnaphthalenes in selected crude oils by two-dimensional capillary GC. Since the method does not comprise any work-up procedure the determination of geochemical parameters (alkylnaphthalene concentration ratios) is performed on the original, untreated crude oil samples. Accordingly, the analytical results reflect the original composition. The influence by evaporational losses in the laboratory is minimized.     

Simple and rapid micellar electrokinetic capillary chromatographic method for simultaneous determination of four antiepileptics in human serum

A very rapid and simple MEKC method was developed for the simultaneous determination of four antiepileptic drugs, ethosuximide (Etho), primidone (Pri), phenytoin (Pht) and carbamazepine (Cbz) in human serum. Sample analysis required only 100 microL of human serum which only needed to be centrifuged, decanted and combined with the running buffer [5.3 mM Na(2)HPO(4)/3.2 mM borax buffer (pH 9.5) containing 55 mM SDS and 3.5% (v/v) acetone]. The analysis was performed in only 10 min into fused-silica capillaries (57 cm total length with 50 microm i.d. and 50 cm to the detector) using the MEKC methodology with diode-array detection at 220 nm. The calibration graphs were established for ethoximide, primidone, phenytoin and carbamazepine between 0 and 20 mg/L. Recoveries were between 85 and 87%. The simplicity of the proposed methodology makes it suitable for routine clinical use, especially for epileptic patients on polytherapy.     

高效毛细管电泳前沿分析法研究酸性药物那格列奈与人血浆白蛋白的结合

用高效毛细管电泳前沿分析法研究了酸性药物那格列奈与人血浆白蛋白的结合常数、结合位点和结合率。使用未涂层的毛细管柱 (4 0cm× 5 0 μmi.d .;有效柱长 32cm) ,磷酸盐缓冲溶液 (pH 7.4 ,离子强度0 .17)为背景溶液 ,在紫外检测波长 2 14nm、运行电压 18kV和重力进样 10 0s的条件下 ,利用那格列奈谱峰的平台高度和游离药物浓度的良好线性关系 (r>0 .999,n =6 ) ,测定了那格列奈的游离药物浓度。固定药物浓度 (2 0 0 μmol L ,2 5 0 μmol L) ,考察不同的蛋白质浓度对结合的影响 ;固定蛋白质浓度 (10 0 μmol L) ,考察不同的药物浓度对结合的影响。实验数据采用非线性拟和程序进行处理 ,得到了那格列奈的蛋白质结合参数。高效毛细管电泳前沿分析法测定的数据重现性良好 (RSD <2 .5 % ,n =3) ,在药代动力学和药效学研究方面具有简便、准确的优点。     

在线标准加入火焰原子吸收光谱法测定钮扣电池中铅和镉

应用火焰原子吸收光谱(FAAS)法测定了钮扣电池中铅和镉的含量,对测定条件作了较详细的研究。用在线双毛细管标准加入法消除了基体的干扰。按所述方法测定电池样品中铅和镉,测定结果的RSD依次为3.58%和5.87%,铅和镉的浓度水平分别为5.4×10-3%和2.3×10-4%(质量分数),回收率结果为93.0%~100.1%(铅)和95.0%~101.0%(镉)。