Determination of urinary prostanoids by capillary gas chromatography/high-resolution mass spectrometry

A stable isotope-dilution gas-chromatography/high-resolution mass spectrometry method for the determination of prostaglandin E₂ (PGE₂) and 6-keto-prostaglandin F_1α (6-keto-PGF_1α) in urine as their methoxime/t-butyldimethylsilyl ether/t-butyl-dimethylsilyl ester derivatives is described. The derivatives are prepared by a novel derivatization scheme in which the pentafluorobenzyl esters are formed prior to the silylation step in which the t-butyldimethylsilyl esters are formed in an apparent exchange reaction. Recoveries through the entire extraction and derivatization procedure are 70.6% for PGE₂ and 64.4% for 6-keto-PGF_1α. Quantitation at mass resolutions approaching 10 000 eliminated all interferences in the PGE₂ chromatograms while lower resolutions were sufficient for 6-keto-PGF_1α. Limits of detection of 50 pg ml^?1 for each prostanoid were obtained. For PGE₂, a lower limit of detection was obtained at a mass resolution of 10 000 (50 pg ml^?1) than was obtained at a mass resolution of 1000 (80 pg ml^?1), illustrating the selectivity of detection.     

Determination of the volatiles from tobacco by capillary gas chromatography with atomic emission detection and mass spectrometry

A new gas chromatograph‐atomic emission detector (GC‐AED) coupled with Deans switching technique for analyzing volatiles from tobaccos were developed. The detector operating parameters (reagent gas pressure and make‐up gas flow rate) were optimized. The detection limits for the elements carbon (193 nm), hydrogen (486 nm) and oxygen (171 nm) ranged 0.05–0.2, 0.05–0.3 and 1–11 ng, respectively, depending on the compound. The sensitivity and linearity for the elements carbon (193 nm), hydrogen (486 nm) and oxygen (171 nm) decreased in the order O>H>C. Calibration curves were obtained by plotting peak area versus concentration, and the correlation coefficients relating to linearity were at least 0.9359. Elemental response factors measured on these channels, relative to the carbon 193‐nm channel, were hydrogen, 0.38–0.48 (mean %RSD=5.64), and oxygen, 0.085–0.128 (mean %RSD=14.9). The evaluation was also done for the new technique and for an established GC‐MS technique for the same real samples. The results of GC‐AED and GC‐MS showed that there was a relatively good agreement between the two sets of data.     

Determination of residual clopidol in chicken muscle by capillary gas chromatography/mass spectrometry

Clopidol was extracted from chicken with acetonitrile, and the extract was evaporated to about 5 mL. The concentrated solution was centrifuged and applied to a glass column filled with basic alumina. The column was eluted with methanol and the methanol was evaporated to dryness. The residue was derivatized with Sylon BFT and analyzed by gas chromatography/mass spectrometry (GC/MS). Mass characteristics of trimethylsilyl derivative of clopidol were interpreted manually. The selected-ion monitoring mode was performed at m/z 191, 248, 263, and 265. A sensitive, reproducible GC/MS method was developed for monitoring residues of clopidol in chickens. All recoveries of the drug from chicken muscle fortified at 1, 10, and 100 ng/g were > 65%, and relative standard deviations were < 15%. The detection limit was about 0.5 ng/g, and the quantitation limit was the lower limit of the standard curve, which was about 1 ng/g.     

Determination of ligustilide in rat blood and tissues by capillary gas chromatography/mass spectrometry

A gas chromatography/mass spectrometry (GC/MS) method was developed to study the pharmacokinetics of ligustilide following oral administration to rats. The method was used for the analysis of samples taken from rats. Biological samples were prepared by liquid-liquid extraction (LLE) using an n-hexane-ether (2:1) solvent mixture for a sample clean-up step and analyzed by GC/MS with a quadrupole MS detector in selected ion monitoring mode (m/z 190). The calibration curves were linear over the concentration range 0.172-8.60 microg/mL (r > 0.99) for blood samples and a different range (r > 0.99) for different tissue samples. The limit of detection (LOD) was 1.0 ng/mL or 1.0 ng/g (three times the signal-noise ratio). Within- and between-day precision expressed as the relative standard deviation (RSD) for the method was 1.58-3.88 and 2.99-4.91%, respectively. The recovery for all samples was >80%, except for liver samples (>70%). The main pharmacokinetic parameters obtained were: T(max) = 0.65 +/- 0.07 h, C(max) = 1.5 +/- 0.2 microg/mL, AUC = 34 +/- 6 h microg/mL and K(a) = 3.5 +/- 0.6/h. The experimental results showed that ligustilide was easily absorbed, but its elimination was slow, from 3 to 12 h after oral administration. The concentrations of ligustilide in rat cerebellum, cerebrum, spleen and kidney were higher than those in other organs.     

气相色谱-质谱联用法测定水果中4,6-二硝基邻甲酚

利用气质联用（GC-MS）技术建立了水果中4,6-二硝基邻甲酚（DNOC）的测定方法。以二氯甲烷提取水果样品中DNOC残留,并使用N-（特丁基二甲基硅）-N-甲基三氟乙酰胺对提取DNOC残留进行衍生化,利用GC-MS选择离子模式（SIM）测定残留DNOC衍生化产物,在苹果和梨中DNOC的添加回收率在70％～110％之间,相对标准偏差RSD〈9％（n=10）,方法的检出限为10μg/kg。     

Determination of polychlorodibenzo-p-dioxins and polychlorodibenzofurans by gas chromatography/tandem mass spectrometry and gas chromatography/triple mass spectrometry in a quadrupole ion trap

The determination of tetra- to octachlorodibenzo-p-dioxins and tetra- to octachlorodibenzofurans (PCCD/Fs) by high-resolution gas chromatography/tandem mass spectrometry (HRGC/MS/MS) and high-resolution gas chromatography/triple mass spectrometry (HRGC/MS(3)) in a quadrupole ion trap, equipped with an external ion source, is presented. MS/MS involves a typical four-step process, namely ionization, parent ion isolation, collision-induced dissociation (CID) and mass analysis of the daughter ions. For the MS(3) experiment, the MS/MS scan function is used with the addition of selected daughter ion isolation, their CID and the mass analysis of second-generation product ions called 'grand-daughter ions.' For both methods, the energies necessary for the CID of the 17 PCDD/Fs were determined and optimized using multiple scan functions with different CID amplitudes. The CID efficiency, defined as the signal ratio of fragment ions detected from the major dissociation channels to molecular ions isolated, was 1.15-2.40 V for parent ion dissociation (MS/MS) and 1.05-1.50 V for daughter ion dissociation (MS(3)) and for all the chloro congeners. The same sensitivity (1 pg microl(-1)) can be reached with both the MS/MS and MS(3) methods and linear responses were obtained between 1 and 100 pg microl(-1) injected.     

Analysis of dinitrofluoranthenes by high resolution capillary gas chromatography/mass spectrometry

This paper reports the retention indices of eighteen of the possible twenty-five dinitrofluoranthene isomers.     

Determination of benzidine in urine using capillary gas chromatography and negative-ion chemical ionisation mass spectrometry

Summary A highly sensitive and specific gas chromatographic-mass spectrometric (GC-MS) assay for the determination of benzidine in urine is reported. It is based on the solvent extraction of the hydrolysed benzidine conjugates, together with the deuterium-labelled benzidine-d₈ added as an internal standard, and a two-phase derivatisation procedure using pentafluoropropionic anhydride (PFPA) in the presence of pyridine as the phase-transfer catalyst. The reaction is complete within 5 min at room temperature. The pentafluoropropyl derivatives are quantified through capillary column GC-MS using selected ion monitoring (SIM) in the negative-ion chemical ionisation mode (NICI). The lower limit of detection for benzidine was 0.5 g/l and the calibration plot showed linearity between 2 g/l and 200 g/l. The recovery of the analyte added to pooled urine was above 82%. Analysis of 20 urine samples from un-exposed persons and 20 urine specimens of workers employed in a polyurethane-making plant using this procedure showed no substances likely to manifest false positive results in the range of interest.     

Identification of oxygenated polycyclic aromatic hydrocarbons in diesel particulate matter by capillary gas chromatography and capillary gas chromatography/mass spectrometry

Summary Using a two-step liquid chromatographic separation on normalphase cartridges, crude extracts of diesel particulate matter can be separated without time-consuming sample handling into special fractions which mainly contain slightly-polar oxygenated polycyclic aromatic hydrocarbons (oxy-PAH) and nitrated polycyclic aromatic hydrocarbons (nitro-PAH). Subsequent analysis was by fused-silica capillary gas chromatography on a SE54 column along with flame-ionisation (GC/FID) and positive-ion electron-impact mass spectrometric detection (GC/MS) respectively. A number of individual oxy-PAH belonging to four different chemical classes (ketones, quinones, anhydrides and aldehydes) and several individual nitro-PAH were characterized by their retention times and mass spectra. Presented at the 15th International Symposium on Chromatography, Nürnberg, October 1984     

毛细管气相色谱法测定菜籽油中脂肪酸组成

采用FFAP毛细管气相色谱法对菜籽油的各组分进行了定性和定量分析.结果表明菜籽油中至少含有从肉豆蔻酸(C140)至鲨油酸(C240)共15种脂肪酸甘油酯.四次平行分析显示各成分含量的标准偏差低于0.33%,绝对偏差不超过0.70%.     

Analysis of Alaskan crude oils by glass capillary gas chromatography/mass spectrometry

Glass capillary gas chromatography/mass spectrometry is used to profile Alaskan crude oil for purposes of origin verification. Alaskan oil, sampled at Valdez, Alaska, and transshipped to the U.S. East Coast, is compared with 21 samples of foreign crude oil using GC/MS techniques in which original data is reconstructed at selected parent and fragment ions to generate a series of chromatographic profiles. Comparison of selected profiles and compositional parameters derived from peak ratios allows distinction of Alaskan oil from many foreign crudes and may be applied to the examination of crude mixtures.     

Determination of volatile priority pollutants in water by purge and trap and capillary column gas chromatography/mass spectrometry

Two wide-bore capillary columns are evaluated for their applicability to the purge-and-trap technique and GC/MS analysis of 34 volatile organics. Neither column is able to completely resolve all 34 compounds, as is also typical of the packed column; however, the analysis is faster than with the packed column (18 to 21 min compared to 30 min), and the column effluent is introduced directly into the mass spectrometer without requiring an open-split interface. Method precision, as assessed from the instrument response at a concentration of 50 micrograms/L per component, is better than +/- 5% for 41% of the compounds using the VOCOL column (diphenyl dimethyl polysiloxane with crosslinking moieties) and for 53% of the compounds using the 007 column (95% methyl 5% phenyl silicone). The instrument response is linear from 20 to 200 micrograms/L for most compounds, and the amounts loaded to either column without serious distortion of the peak shape or resolution can be as high as 5 micrograms per component. Because the VOCOL column resolved more compounds than the 007 column within approximately the same analysis time, this column is further tested for performance with groundwater samples.     

Limits in arson debris analysis by capillary column gas chromatography/mass spectrometry

Sample enrichment technology and instrumental sensitivity are no longer limiting factors in arson debris analysis. When pyrolyzed, petroleum based composite materials may produce artifacts. Urban air is another major source of interference since some of the components typically found in air, in particular alkylated aromatic hydrocarbons, are customarily used as indicators for the presence of gasoline. It is suggested to replace qualitative analysis with a quantitative approach, taking the sample matrix into consideration.     

Determination of lovastatin acid in serum by gas chromatography/mass spectrometry

The acid form of lovastatin, an HMG-CoA reductase inhibitor, was analyzed by gas chromatography/negative-ion chemical ionization mass spectrometry after derivatization with pentafluorobenzyl bromide and bis-(trimethylsilyl)trifluoroacetamide (BSTFA). Mass spectrometry of this derivative produced a dominant [M-181]- ion under chemical ionization conditions using ammonia as the reagent gas. The limit of detection was approximately 2 pg injected on column.     

捕集阱顶空气相色谱/质谱法测定水中的二氯一溴甲烷

建立了捕集阱顶空气相色谱/质谱测定水中二氯一溴甲烷的方法。采用正交实验设计对平衡温度、平衡时间、循环次数3个参数进行了优化,在平衡温度70 ℃、平衡时间20 min、循环次数2次的优化条件下,对水中的二氯一溴甲烷进行测定。结果显示,在0.1～10.0 μg/L范围内,二氯一溴甲烷的质量浓度和峰面积呈良好的线性关系,相关系数为0.9991。方法的检出限(S/N=3)为0.03 μg/L,定量限(S/N=10)为0.1 μg/L,回收率为83.1%～111.3%,相对标准偏差为1.7%～5.2%(n=6)。将该方法应用于水中二氯一溴甲烷的定性定量分析,效果良好。     

气相色谱-质谱法测定化妆品中的防晒剂

采用气相色谱-质谱法测定了化妆品中11种防晒剂，通过对提取溶剂、提取条件的选择和线性、灵敏度、精密度、回收率等的研究，建立了测定化妆品中防晒剂的方法，11种防晒剂的平均回收率(n＝5)在98．2％-101．2％之间，相对标准偏差(n＝5)在0．3％-1．6％之间。     

气相色谱-质谱联用法测定大蒜中的嘧霉胺、噻螨酮残留量

建立了大蒜中嘧霉胺、噻螨酮残留量的气相色谱-质谱联用(GC-MS)检测方法.大蒜样品经过微波处理,乙酸乙酯提取,硅胶柱净化,采用EI源、选择离子监测方式(SIM),并通过基质添加标准消除了基质效应.结果证明,方法定量下限噻螨酮为0.01 mg/kg,嘧霉胺为0.001 mg/kg,加标回收率范围73.5%～97.8%,相对标准偏差在2.3%～12.5%之间,该方法可实现快速、灵敏、准确的检测分析.     

Determination of the volatile composition in brown millet, milled millet and millet bran by gas chromatography/mass spectrometry

The volatile compounds from brown millet (BM), milled millet (MM) and millet bran (MB) were extracted using simultaneous distillation/extraction with a Likens-Nickerson apparatus. The extracts were analysed using gas chromatography coupled with mass spectrometry (GC-MS). A total of 65 volatile compounds were identified in all of the samples. Among these compounds, 51, 51 and 49 belonged to BM, MM and MB, respectively. Aldehydes and benzene derivatives were the most numerous among all of the compounds. Three compounds (hexanal, hexadecanoic acid and 2-methylnaphthalene) were dominant in the BM and MM materials. Eight compounds (hexanal, nonanal, (E)-2-nonenal, naphthalene, 2-methylnaphthalene, 1-methylnaphthalene, hexadecanoic acid and 2-pentylfuran) were dominant in the MB materials. Apart from the aromatic molecules, which were present in all fractions, compounds present only in BM, MM or MB were also identified.     

凝胶渗透色谱-气相色谱-质谱测定花生中乙草胺的残留量

建立了以凝胶渗透色谱(GPC)净化和气相色谱-质谱(GC-MS)技术快速测定花生中乙草胺残留量的方法.经乙腈提取,共提物中的油脂和色素经GPC去除,目标农药采用GC-MS-SIM方式进行定性和定量分析.方法的回收率90%～120%;相对标准偏差2.5%～10%.方法定量限0.005 μg/g.     

凝胶渗透色谱净化-气质联用法测定土壤中三嗪类除草剂

建立了以超声波提取、凝胶渗透色谱净化(GPC)、HP-5 MS石英毛细管柱分离、E1离子源质谱法测定土壤中13种三嗪类除草剂的多残留检测方法.三嗪类除草剂的添加水平为0.010～0.100 mg/kg时,平均回收率为72.1%～118.3%,相对标准偏差为2.6%～19.8%(n=4);方法的检出限为0.30～2.50μg/kg.