共查询到20条相似文献,搜索用时 758 毫秒
1.
Park HE Yang SO Hyun SH Park SJ Choi HK Marriott PJ 《Journal of separation science》2012,35(3):416-423
The quantitative performance of a simple home‐built preparative gas chromatography (prep‐GC) arrangement was tested, incorporating a micro‐fluidic Deans switch, with collection of the target compound in a deactivated uncoated capillary tube. Repeat injections of a standard solution and peppermint sample were made into the prep‐GC instrument. Individual compounds were eluted from the trapping capillary, and made up to constant volume. Chloronaphthalene internal standard was added in some cases. Recovered samples were quantitatively assayed by using GC‐MS. Calibration linearity of GC‐MS for menthol standard area response against number of injections (2–20 repeat injections) was excellent, giving R2 of 0.996. For peppermint, menthol correlation over 2–20 repeated injections was 0.998 for menthol area ratio (versus IS) data. Menthone calibration for peppermint gave an R2 of 0.972. 1H NMR spectroscopy was conducted on both menthol and menthone. Good correspondence with reference spectra was obtained. About 80 μg of isolated menthol and menthone solute was collected over a sequence of 80 repeat injections from the peppermint sample, as assayed by 600 MHz 1H NMR analysis (~100% recovery for menthol from peppermint). A procedure is proposed for prediction of number of injections required to acquire sufficient material for NMR detection. 相似文献
2.
3.
Summary Gas chromatography has been used to study the kinetics of evolution of volatiles from polypropylene samples (at 70°C). Correlation chromatography (CC) and the trapping of volatiles on Tenax sorbents and activated charcoal were employed to improve the detector signal. As a reference, the kinetics of gas evolution was studied by making a series of direct single injections of polymer head-space gas on a GC column. The results of trapping differed from those obtained by single injection. However, the data from single injections and CC were in good agreement. The CC method was found to offer far more operator convenience for dynamic head-space analysis than sample trapping, being less subject to operator errors. 相似文献
4.
Christian Rühle Graham T. Eyres Sylvia Urban Jean-Pierre Dufour Paul D. Morrison Philip J. Marriott 《Journal of chromatography. A》2009,1216(30):5740-5747
The preparative scale isolation of multiple components from an essential oil matrix is described using multidimensional gas chromatography (prep-MDGC) which allows their further characterisation by mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy. Menthol, linalyl acetate, carvone and geraniol were isolated individually, and were also collected in various combinations. It was demonstrated to be possible to collect multiple selected components from numerous repeat injections of the sample, to permit increased mass recovery from an external cryotrap collection device. Peak retention times remained reproducible (<0.3 s) over the repeated injections and switching events. This methodology may be utilised to confirm peak identity or to produce unique mixed-component reference standards, for instance to allow their identification in other samples using GC/MS, or identify them in comprehensive two-dimensional gas chromatography (GC × GC) analysis. 相似文献
5.
P. L. Wylie 《Chromatographia》1986,21(5):251-258
Summary A convenient procedure has been described for enhancing the sensitivity of equilibrium headspace gas chromatography. The technique
involves the cryogenic focusing of headspace vapors at the head of a 0.32 mm fusedsilica capillary column which has been coupled
to a packed column injection port. Cryofocusing is accomplished automatically by cooling the GC oven and results in enhanced
sensitivity with improved resolution. With this simple focusing technique no sample splitting is required which gives at least
a 10-fold increase in sensitivity. A Multiple Headspace Injection (MHI) technique has been described which allows several
rapid headspace injections to be made at the start of a single chromatographic run. Cryofocusing causes the injections to
be superimposed, thus increasing the sensitivity even further. These procedures have been demonstrated for flavor and aroma
analyses of toothpaste and soft drink samples.
Presented at the Symposium on Headspace GC, National American Chemical Society Meeting, Chicago, Ill., September 8–13, 1985 相似文献
6.
7.
Clean-up of plasma extracts by gel permeation chromatography during analysis of isosorbide nitrates by capillary gas chromatography. 总被引:1,自引:0,他引:1
This work describes how gel permeation chromatography (GPC) can be used for sample clean-up to reduce the fouling of the column in an automated on-column injector. The analytes were isolated from plasma together with the internal standard (isomannide dinitrate) by liquid-liquid extraction on Extrelut silica columns. The extracts were evaporated and reconstituted in tetrahydrofuran for separation of the analytes from non-volatile plasma components by GPC on a styrene-divinylbenzene column with 100 A pore size. A programmable autosampler with an additional three-way valve was used for injection and fraction collection. The molecular weight fraction between 100 and 700 a.m.u. was collected and transferred to the on-column autosampler for capillary gas chromatography on a 30-m column butt-connected to a 0.2-m pre-column. The pre-column was replaced after 50 sample injections. When the GPC purification was excluded from the work-up procedure a deposit of non-volatile components was formed at the injection zone of the pre-column which resulted in excessive peak-tailing after only five or six injections of plasma extract. The limit of determination was 0.2 ng/ml plasma for isosorbide dinitrate and 0.4 ng/ml for the mononitrates. 相似文献
8.
In this work,a reliable and sensitive method for detecting polybrominated diphenyl ethers(PBDEs) has been developed by the combination of liquid–liquid extraction and gas chromatography–mass spectrometry.PBDEs were extracted from a large volume of water by liquid–liquid extraction and purified by silica gel chromatography.In order to reduce the deviation,dibromobiphenyl was exploited as the internal standard to minimize differences among the injections.The quantification was performed using an external standard.Good linear correlation coefficients(0.991) and a wide linearity range(1.0–500.0 ng/L) indicated the steadiness of the proposed method.Moreover,the satisfactory recovery(75%)suggested that successful determination of PBDEs in river water had been achieved.Furthermore,the deduction behavior of PBDEs in river water could be inferred according to the results. 相似文献
9.
10.
建立顶空气相色谱法测定富氢水中氢气的方法。采用顶空的方式将水中的微量氢气转移到气相中,通过分子筛色谱柱分离,用热导检测器测定。分析条件如下:分流比为5∶1,气液体积比为1.2∶1,平衡温度为40℃,平衡时间为15 min。水中氢气的质量浓度在0.080~1.603 mg/L范围内与色谱峰面积成良好线性关系,线性相关系数为0.999,方法检出限为0.005 mg/L。样品加标回收率为91.03%~94.25%,测定结果的相对标准偏差为0.61%~2.32%(n=6)。该法可用于富氢水中氢气的测定。 相似文献
11.
研制了可与全二维气相色谱联用的高通量飞行时间质谱仪,并进行了性能水平测试。设计采用新型高灵敏度电子轰击源及具有垂直引入、双推斥脉冲、二级反射式结构的飞行时间质量分析器,结合高于20 kHz的推斥频率,可获得质量范围1~1000 amu,质量分辨>1000(m/z 219,ADC采集卡),检出限低于1 pg,线性动态范围超过4个数量级,同时最快可达400谱/s的高采集速度,完全满足全二维气相色谱与飞行时间质谱联用的检测要求。与一款完全国产化的全二维气相色谱仪联用,实现对石油、香精、环境等多个领域复杂样品的分析,获得令人满意的检测结果,显示了此质谱仪器与全二维气相色谱联用的适用性及其在复杂样品体系全组分分析中的应用潜力。 相似文献
12.
催化裂化汽油中硫化物类型分布的气相色谱-硫化学发光检测的方法研究 总被引:18,自引:2,他引:16
采用气相色谱-硫化学发光检测器(GC-SCD),建立了催化裂化汽油(FCC汽油)中各种硫化物类型分布的分析方法。考察了色谱条件对催化裂化汽油中各种硫化物分离的影响,定性了某催化裂化汽油中的58个硫化物。采用该方法,硫化物中的硫在其质量浓度为0.5~800.0 mg/L时,其峰面积与质量浓度呈较好的线性关系,相关系数达0.999,其响应与硫化物的类型无关。FCC汽油中几种主要硫化物(噻吩、正丁硫醇、2-甲基噻吩、3-甲基噻吩、2,4-二甲基噻吩)的浓度测定值的相对标准偏差(RSD)均小于5.0%。当信噪 相似文献
13.
Non‐polar lipids characterization of Quinoa (Chenopodium quinoa) seed by comprehensive two‐dimensional gas chromatography with flame ionization/mass spectrometry detection and non‐aqueous reversed‐phase liquid chromatography with atmospheric pressure chemical ionization mass spectrometry detection 下载免费PDF全文
Chiara Fanali Marco Beccaria Simona Salivo Peter Tranchida Giusy Tripodo Sara Farnetti Laura Dugo Paola Dugo Luigi Mondello 《Journal of separation science》2015,38(18):3151-3160
A chemical characterization of major lipid components, namely, triacylglycerols, fatty acids and the unsaponifiable fraction, in a Quinoa seed lipids sample is reported. To tackle such a task, non‐aqueous reversed‐phase high‐performance liquid chromatography with mass spectrometry detection was employed. The latter was interfaced with atmospheric pressure chemical ionization for the analysis of triacylglycerols. The main triacylglycerols (>10%) were represented by OLP, OOL and OLL (P = palmitoyl, O = oleoyl, L = linoleoyl); the latter was present in the oil sample at the highest percentage (18.1%). Furthermore, fatty acid methyl esters were evaluated by gas chromatography with flame ionization detection. 89% of the total fatty acids was represented by unsaturated fatty acid methyl esters with the greatest percentage represented by linoleic and oleic acids accounting for approximately 48 and 28%, respectively. An extensive characterization of the unsaponifiable fraction of Quinoa seed lipids was performed for the first time, by using comprehensive two‐dimensional gas chromatography with dual mass spectrometry/flame ionization detection. Overall, 66 compounds of the unsaponifiable fraction were tentatively identified, many constituents of which (particularly sterols) were confirmed by using gas chromatography with high‐resolution time‐of‐flight mass spectrometry. 相似文献
14.
建立浓海水中氯酚的顶空固相微萃取气相色谱法检测方法。采用顶空固相微萃取对海水淡化排放的浓海水样品中2,4,6-三氯酚(2,4,6-TCP)和五氯酚(PCP)进行分离富集,气相色谱-电子捕获检测器(μECD)测定浓海水样品中2,4,6-TCP和PCP的含量。讨论了萃取时间、萃取温度、水样盐度等实验条件对富集效率的影响,确定了萃取时间为40 min,萃取温度为60℃。2,4,6-TCP,PCP的质量浓度在0.500~20.0μg/L范围内与其色谱峰面积呈良好的线性关系,线性相关系数均大于0.999,2,4,6-TCP和PCP的检出限(2S/N)分别为0.055,0.128μg/L,测定结果的相对标准偏差为3.65%~11.4%(n=6),加标回收率为73.5%~119.0%。该方法快速,灵敏度高,适合于浓海水中氯酚的分析。 相似文献
15.
The gas chromatography/mass spectrometric assay method was developed for the determination of 13 non‐steroidal anti‐inflammatory drugs (NSAIDs) in river water. Extraction was achieved by a liquid‐phase extraction procedure using methylene chloride. The extract was reacted for 30 min at 80°C based on the formation of methyl ester with 1.0 M HCl in methanol and extraction of the derivative with ethyl acetate, which was then measured by gas chromatography‐mass spectrometry. The limit of quantification of NSAIDs was 1.0–60 ng/L and the calibration curve showed linearity being greater than r=0.997. The method was used to analyze ten river water samples from various regions in Korea. Diclofenac, indoprofen, ketoprofen and loxoprofen were detected at concentration of up to 1.29 μg/L in river water. The developed method may prove valuable for use in the national monitoring project of NSAIDs in surface water. 相似文献
16.
Radka Pechancov Changling Qiu Jonathan Smuts Karel Lemr Kevin A. Schug 《Journal of separation science》2019,42(2):556-565
This work focused on the development and validation of the analytical procedure using gas chromatography equipped with vacuum‐ultraviolet detection for the specific and sensitive determination of nine photoinitiators in food packages. Subsequently, a comparison of the combination of vacuum ultraviolet spectroscopy with gas chromatography and a developed gas chromatography with mass spectrometry method was performed. The vacuum‐ultraviolet spectra of all tested photoinitiators were collected and found to be highly distinct, even for isomers. Under the optimal conditions, the limits of detection for nine photoinitiators ranged from 1 to 5 mg/L using vacuum ultraviolet detection and from 0.15 to 0.5 mg/L using mass spectrometric detection. Both techniques were successfully applied for screening of photoinitiators in seven kinds of food packages and the obtained data showed good agreement (the relative difference was between 3 and 18%). The variability in concentrations found in triplicate samples was assessed to be below 18%. Predominantly benzophenone was found in all analysed samples in the range of 0.31–4.23 mg/kg. It appears to be preferably selected by food packaging manufacturers. This study proposes a new simple and sensitive technique used for analysis of photoinitiators that could be a good alternative to gas chromatography with mass spectrometry. 相似文献
17.
The essential oil of the flowers of Tridax procumbens L. was obtained by hydro-distillation and analyzed by gas chromatography equipped with a flame ionization detector (GC-FID) and gas chromatography coupled with mass spectrometry (GC/MS). Twenty-six compounds were identified, which comprised 90.6% of the total constituents. The most abundant compound was (Z)-falcarinol (25.9%), followed by alpha-selinene (15.3%), limonene (8.3%) and zerumbone (4.3%). Antimicrobial activity was tested against six Gram-positive and eight Gram-negative bacteria, and three fungi. The oil was active against the tested Gram-positive bacteria at a concentration range of 0.14 +/- 0.03 - 0.57 +/- 0.05 mg/mL, while 0.67 +/- 0.12 - 4.58 +/- 0.41 mg/mL was effective against the studied Gram-negative bacteria. Remarkable antifungal activity was found against the tested fungi at a concentration range of 0.06 +/- 0.008 - 0.10 +/- 0.01 mg/mL. 相似文献
18.
Low‐temperature headspace‐trap gas chromatography with mass spectrometry for the determination of trace volatile compounds from the fruit of Lycium barbarum L. 下载免费PDF全文
The total saccharides content of Lycium barbarum L. is very high, and a high temperature would result in saccharide decomposition and the emergence of a large amount of water. Moreover, the volatile compounds from the fruit of L. barbarum L. are rather low in concentration. Hence, it is difficult for a conventional headspace method to study the volatile compounds from the fruit of L. barbarum L. Since headspace‐trap gas chromatography with mass spectrometry is an excellent method for trace analysis, a headspace‐trap gas chromatography with mass spectrometry method based on low‐temperature (30°C) enrichment and multiple headspace extraction was developed to explore the volatile compounds from the fruit of L. barbarum L. The headspace of the sample was extracted in 17 cycles at 30°C. Each time, the compounds extracted were concentrated in the trap (Tenax TA and Tenax GR, 1:1). Finally, all the volatile compounds were delivered into the gas chromatograph after thermal desorption. With the method described above, a total of 57 compounds were identified. The identification was completed by mass spectral search, retention index, and accurate mass measurement. 相似文献
19.
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. 相似文献
20.
聚醚砜酮涂层纤维顶空固相微萃取-气相色谱法分析水中痕量的酚类化合物 总被引:1,自引:0,他引:1
应用自制的聚醚砜酮(PPESK,30 μm)涂层纤维,采用顶空固相微萃取-气相色谱法测定水中痕量的酚类化合物。优化了固相微萃取温度、萃取时间、pH值和离子强度。方法的检出限为0.003~0.041 μg/L,相对标准偏差低于16%(n=5)。将PPESK涂层纤维与商品化的聚丙烯酸酯涂层纤维对比,结果表明PPESK萃取酚类化合物有较高的萃取富集倍数。用所制备的PPESK萃取头分析自来水、海水等实际水样,20 μg/L添加水平下的回收率分别为100.5%~111.8%和94.8%~117.3%。 相似文献