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121.
A novel methodology in on-line pyrolysis-gas chromatography (Py-GC) for the fast analysis of fatty acids in vegetable oils with minimal sample treatment and the use of non-toxic reagents is described. Pyrolysis at 500 degrees C for 10 s of sub-microgram quantity of vegetable oil dissolved in dimethyl carbonate (DMC) and in the presence of nanopowder titanium silicon oxide resulted in the production of fatty acid methyl esters (FAMEs) as unique products. Pyrolysis performed by means of a resistively heated filament pyrolyser interfaced to a GC-MS apparatus enabled the direct analysis of evolved FAMEs. The DMC/Py-GC-MS analysis was tested on soybean, coconut, linseed, walnut and olive oil and the results compared to the classical BF(3)-methanol as reference methodology. The DMC method exhibited a lower precision and was biased towards lower levels of polyunsaturated fatty acids (PUFA) in comparison to the BF(3)-methanol method, but was more advantageous in terms of reduced sample treatment, waste generation and risk factors of employed chemicals. 相似文献
122.
Two new marine sediment standard reference materials (SRMs) for the determination of organic contaminants 总被引:3,自引:0,他引:3
Wise SA Poster DL Schantz MM Kucklick JR Sander LC Lopez de Alda M Schubert P Parris RM Porter BJ 《Analytical and bioanalytical chemistry》2004,378(5):1251-1264
Two new marine sediment standard reference materials (SRMs), SRM 1941b Organics in Marine Sediment and SRM 1944 New York/New Jersey Waterway Sediment, have been recently issued by the National Institute of Standards and Technology (NIST) for the determination of organic contaminants including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyl (PCB) congeners, and chlorinated pesticides. Both sediment SRMs were analyzed using multiple analytical methods including gas chromatography/mass spectrometry (GC/MS) on columns with different selectivity, reversed-phase liquid chromatography with fluorescence detection (for PAHs only), and GC with electron capture detection (for PCBs and pesticides only). SRM 1941b has certified concentrations for 24 PAHs, 29 PCB congeners, and 7 pesticides, and SRM 1944 has certified concentrations for 24 PAHs, 29 PCB congeners, and 4 pesticides. Reference concentrations are also provided for an additional 58 (SRM 1941b) and 39 (SRM 1944) PAHs, PCB congeners, and pesticides. SRM 1944, which was collected from multiple sites within New York/New Jersey coastal waterways, has contaminant concentrations that are generally a factor of 10–20 greater than SRM 1941b, which was collected in the Baltimore (Maryland) harbor. These two SRMs represent the most extensively characterized marine sediment certified reference materials available for the determination of organic contaminants.Electronic Supplementary Material Supplementary material is available in the online version of this article at . A link in the frame on the left on that page takes you directly to the supplementary material. 相似文献
123.
Multiple-separation and -detection are two approaches applied at the identification of analytes in chromatography. Using them depends on the physico-chemical properties and elemental content of the analytes. When physico-chemical properties are similar multiple-separation gives better opportunities for the identification. In this case, the efficiency of the columns is very important. When analytes contain some characteristic groups as--NO2, halogen, or nitrogen atoms then multiple-detection will be more useful. The sensitivity and/or selectivity of the detectors increase reliability of identification significantly. 相似文献
124.
125.
红外光谱反应出的是特征化学基团的振动 ,对于高聚物的具体单体组成分析 ,只能借助于紫外光谱、核磁共振及质谱进行综合判断才能得到圆满的鉴定结果[1,2 ] 。本工作针对在红外光谱仪不能分辨的情况下通过气相色谱 质谱联用技术进行综合分析鉴定 ,结果可为其它高聚物分析研究提供实验依据。1 实验1 1 仪器及试验条件未知高聚物试样为白色颗粒状 (晨光化工二厂 )。SYSTEM2 0 0 0FTIR ,PE公司造IR谱仪 ;CDS2 0 0 0铂金丝裂解器 ,裂解室温度 2 5 0℃ ,裂解温度 6 0 0℃ ,升温速率 1 40℃ ms;HP6 890型 ,Compond… 相似文献
126.
K. H. C. Baser H. R. Nuriddinov T. Ozek B. Demirci N. Azcan A. M. Nigmatullaev 《Chemistry of Natural Compounds》2002,38(1):51-53
The herbal parts of Arischrada korolkowii (Regel et Schmalh.) Pobed. (Lamiaceae) growing in Uzbekistan were hydrodistillated to yield 1.1% of essential oil. The essential oil was analyzed by GC/MS. Eighty eight compounds were characterized representing 98% of the essential oil with 1,8-cineole (29.3%), camphor (9.8%), -caryophyllene (8.5%), bornyl acetate (7.7%), caryophyllene oxide (7.2%), and borneol (5.6%) as the main constituents. 相似文献
127.
The glycosides of volatile compounds and the essential oil were isolated from wild Mentha longifolia. After the enzymatic hydrolysis of glycosides, fourteen volatile aglycones were identified by GC/MS. The main aglycones were eugenol, 2-phenylethanol, benzyl alcohol, lavandulol, trans- and cis-carveol, 3-octanol, and 3-hexen-1-ol. The content of aglycones was 40.85 mg kg-1 of dried plant material. The main components of the essential oil (yield 0.93 w/w) were carvone, piperitenone oxide, limonene, and -caryophyllene. Eugenol, carveol, 3-octanol, and -terpineol were identified in the aglycones and in the essential oil. 相似文献
128.
《Analytical letters》2012,45(14):3077-3092
ABSTRACT The application of trap and desorption GC/MS to monitoring of sixteen PAHs in the exhaust emissions from motorcycles was investigated. The time of sampling and analysis for one sample is in 40 minutes. The relative standard deviations were estimated from 20% to 34% for monitoring the total concentrations of PAHs from the emissions of motorcycles. The PAH concentrations appeared to show distinct variations with the stroke, engine size and the aging of motorcycles. The predominate of PAHs in the emissions of motorcycle were naphthalene, fluorene, anthracene, fluoranthene and pyrene. Naphthalene exhibited the highest concentration that was obtained over 79% of the total concentration of sixteen PAHs in the emissions of the over nine years old motorcycles. 相似文献
129.
《Analytical letters》2012,45(13-14):2783-2790
Abstract A method for preparing [21,21,22-2H3] digoxin by proton exchange with D2O under high temperature and basic conditions is described. Loss of signal for the protons at C21 and C22 upon deuteration, with retention of structural integrity for the remainder of the parent compound, is established with high resolution proton NMR spectroscopy. Confirmation of the site of deuterium exchange and relative abundance of the species 2H0:2H1:2H2:2H3 is demonstrated by capillary gas chromatography - mass spectrometry (GC-MS) of the trimethylsilyl derivative of the steroidal component of digoxin, digoxigenin. 相似文献
130.
《Analytical letters》2012,45(5-6):613-624
Hazardous levels of melamine in food and feed products have been of great concern after the outbreak of contamination reported in Chinese commodities in 2008. Despite the existence of several analytical methods for melamine (MEL) detection in food, few provide a full validation data set, especially when MEL and cyanuric acid (CYA) are analyzed simultaneously. The aim of this study was to validate an analytical methodology for MEL and CYA analysis in foodstuffs by GC-MS after trimethylsilylation with N,O-bis(trimethylsilyl)trifluoroacetamide. Linearity was obtained in the range of 0.4 to 800 mg/kg for both compounds, with limits of detection (LODs) of 0.15 and 0.05 mg/kg for MEL and CYA, respectively. Screening in 20 food products [3 soya milk powder, 1 baby milk powder, 3 soya powder, 13 diversified cookies and biscuits (8 from China and 2 from Portugal), and 3 dog food) revealed MEL incidence in 55% of the cases, with a maximum concentration of 3.4 mg/kg. CYA was not detected in all samples. 相似文献