共查询到20条相似文献,搜索用时 10 毫秒
1.
Improvements have been described in the apparatus and methods employed in determining polycyclic aromatic hydrocarbons in tobacco smoke by alumina-column chromatography and automatic ultra-violet spectrophotometry 相似文献
2.
Improved gas chromatographic determination of nicotine in environmental tobacco smoke 总被引:2,自引:0,他引:2
A rapid gas chromatographic procedure with an analysis time of 5 min was developed for the determination of environmental nicotine collected on sorbent tubes containing XAD-4 resin. In validating this procedure, severe temporal losses of nicotine were observed for solutions in glass sample vials waiting in a queue in an autosampler tray for analysis. These losses were traced to adsorptive interactions of nicotine with the glass surface of the vials. The use of N-ethylnornicotine as the internal standard or the addition of triethylamine to all solutions were both successful in producing constant response ratios of nicotine to internal standard. Owing to the limited availability and expense of N-ethylnornicotine, our current procedure calls for the addition of triethylamine to all nicotine solutions at the 0.01% V/V level and the use of quinoline as internal standard. 相似文献
3.
Bruce M. Hasch Melchior A. Meilchen Sang-Ho Lee Mark A. McHugh 《Journal of Polymer Science.Polymer Physics》1992,30(12):1365-1373
Cloud-point data to 180°C and 2,800 bar are presented for three poly(ethylene-co-methyl acrylate) copolymers [10, 31, and 41 mol % methyl acrylate (MA)] and for polyethylene in ethylene, ethane, propylene, and propane. At low concentrations of MA in the backbone of the copolymer, the saturated hydrocarbons are better solvents for the copolymer than their olefinic analogs because polarizability drives the phase behavior. For the higher MA-content copolymers, which have more polar repeat units, the unsaturated hydrocarbons are better solvents owing to favorable quadrupolar interactions between the solvent and the polymer segments. The cloud-point curves of the high MA-content copolymers in the unsaturated hydrocarbons are shifted to very high temperatures to overcome strong acrylate-acrylate interactions in the polymer. In fact, the 41 mol % MA copolymer cannot be dissolved in propane at temperatures to 180°C and pressures to 2,800 bar even though the copolymer is predominantly ethylene, while the same copolymer dissolves in propylene at 40°C and at pressures as low as 1,400 bar. Although the Sanchez-Lacombe equation of state is used to model the cloud-point curves, two temperature-dependent mixture parameters are needed for a good fit of the data. © 1992 John Wiley & Sons, Inc. 相似文献
4.
5.
E. Häsänen P. K. G. Manninen K. Himberg V. Väätäinen 《Journal of Radioanalytical and Nuclear Chemistry》1990,144(5):367-374
The chlorine and bromine contents in tobacco and tobacco smoke in both the particulate and gaseous phases were studied by neutronactivation analysis. Methyl chloride and methyl bromide concentrations were measured in the gaseous phase by gas-liquid chromatography — mass spectrometry. The chlorine and bromine contents in nine brands of cigarettes were on the average as follows: Tobacco—6600 ppm chlorine and 110 ppm bromine. Cigarette smoke, particulate phase—68 g chlorine and 1 g bromine per cigarette. Cigarette smoke, gaseous phase—90 g chlorine and 5 g bromine per cigarette. In the gaseous phase methyl chloride accounted for 60% of the total chlorine and methyl bromine for 80% of the total bromine. 相似文献
6.
A gas chromatograph/mass-selective detection (GC/MS) method has been developed and validated for the quantitation of 16 polycyclic aromatic hydrocarbons found in mainstream tobacco smoke condensate. The utilization of two types of solid-phase extraction media combined with capillary column technology removed matrix interferences, afforded a significant reduction in analysis run time, and increased accuracy. Also, the addition of a chilled impinger was used to trap semi-volatile polycyclic aromatic hydrocarbons and to provide more accurate data. This was done without sacrificing the repeatability, reproducibility, and precision obtained in previously published methods. The development and validation studies discussed in this paper resulted in an improved, robust analytical method capable of increasing laboratory capacity and reducing sample reporting time. 相似文献
7.
低分子量聚丙烯酸钠的合成 总被引:9,自引:0,他引:9
低分子量聚丙烯酸及其钠盐广泛应用于造纸工业 ,随着高浓度涂布机的引进和铜板纸生产的发展 ,对分散剂的要求越来越大 ,因低分子量聚丙烯酸钠具有提高颜料的细度、分散体系的稳定性 ,提高纸张的柔软性、强度、光泽、白度等优点 ,所以低分子量丙烯酸在造纸工业上越来越受到重视。低分子量聚丙烯酸钠可用不同的方法合成[1,2 ] ,但都是在比较高的温度进行 ,并且要蒸馏回收大量的链转移剂 ,操作费时、耗能。本实验在较低温度下以氧化 还原催化剂直接合成了低分子量聚丙烯酸钠 ,经造纸厂实际应用试验证明 ,该分散剂可单独或与无机磷酸盐分散剂复… 相似文献
8.
9.
Determination of ammonia in tobacco and smoke 总被引:1,自引:0,他引:1
A gas chromatographic method has been developed for the determination of ammonia in tobacco and smoke. Ammonia is liberated from tobacco by a microdiffusion technique using a Conway diffusion cell. Bubbler traps containing dilute sulphuric acid are used to collect the ammonia from smoke. 相似文献
10.
U. C. Mishra G. N. Shaikh S. Sadasivan 《Journal of Radioanalytical and Nuclear Chemistry》1986,102(1):27-35
Trace elements in tobacco and tobacco smoke of a large number of commonly available brands of cigarettes were analyzed by energy dispersive X-ray fluorescence. This work supplements the data on same samples gathered by INAA and reported earlier. Data on some toxic elements like Pb, Cu and Ni that could not be measured by INAA are presented here. A number of chewing and snuff tobacco samples were also analyzed. The concentrations of Ca, K, Cl, Br, Cu, Fe, Ni, Pb, Rb, Sr, Ti and Zn in all these samples are presented and their relative hazards are discussed. 相似文献
11.
12.
Heura Llaquet Simona Pichini Xavier Joya Esther Papaseit Oriol Vall Julia Klein Oscar Garcia-Algar 《Analytical and bioanalytical chemistry》2010,396(1):379-399
The measurement of nicotine and its major metabolites cotinine and trans-3´-hydroxicotinine together with other minor metabolites (e.g., cotinine N-oxide, cotinine, and trans-3´-hydroxicotinine glucuronides) in conventional and nonconventional biological matrices has been used as a biomarker to assess the exposure to environmental tobacco smoke during childhood. The determination of these substances in matrices such as amniotic fluid, meconium, and fetal hair accounts for prenatal exposure to cigarette smoking at different stages of pregnancy. Nicotine and its metabolites in cord blood, neonatal urine, and breast milk are useful for determining acute exposure to drugs of abuse in the period immediately before and after delivery. Cotinine measurement in children’s blood and urine and nicotine and cotinine measurements in children’s hair constitute objective indexes of acute and chronic exposure during infancy, respectively. However, for monitoring and categorizing cumulative exposure to environmental tobacco smoke during the entire childhood, including the prenatal period, the assessment of nicotine in teeth has been proposed as a promising noninvasive tool. This article reviews the usefulness of measurement of nicotine and its metabolites in different fetal and pediatric biological matrices in light of noninvasive collection, time window of exposure detection, and finally clinical application in pediatrics. 相似文献
13.
S L Kopczynski 《Journal of chromatography. A》1989,463(2):253-260
Multidimensional gas chromatographic analysis of air particles for the tobacco alkaloid cotinine is described. The analytical procedure requires little sample preparation. Unambiguous identification of cotinine and nicotine in cigarette smoke and indoor air samples was achieved by precise, reproducible retention times observed with two parallel analytical columns of different polarities and a nitrogen-specific detector. Further investigation of smoking and environmental variables is needed to validate the use of cotinine as a marker compound for environmental tobacco smoke particulate matter. 相似文献
14.
Sterically hindered olefins like norbornene, dimethanooctahydronaphthalene (DMON), 4‐methylpentene, and 3‐methylbutene can be copolymerised with ethene by metallocene/MAO catalysts. Different C2‐, Cs‐ and C1‐symmetric and meso‐zirconocenes were used. Only isolated and alternating norbornene sequences but no norbornene blocks are formed by substituted [Me2C(Cp‐R)(Flu)]ZrCl2 catalysts. The alternating microstructure leads to melting points up to 270°C for ethene‐norbornene copolymers and up to 380°C for the semi‐crystalline alternating copolymer of ethene and DMON. Other sterically hindered olefins such as 3‐methylpentene build more blocky structures with high glass transition temperatures. The mechanism for the insertion reaction of the different catalysts is discussed. 相似文献
15.
Summary In order to assess the pathways of chlorinated benzenes and toluenes, hexachlorobutadiene and polychlorinated biphenyls in the environment capillary gas chromatographic methods have been developed for analysis of water, sediments and biological samples. Compound recoveries are reported from water, using liquid-liquid extraction with hexane, and from sediments and fish, using soxhlet extraction with hexane/acetone. After suitable cleanup, hexane extracts are chromatographed on a duel fused silica column arrangement (OV1 and SE54 with electron capture detectors for quantitation. The application of these procedures to environmental analysis is discussed.Presented at the 14th International Symposium on Chromatography London, September, 1982 相似文献
16.
17.
Maria G. Lourenço Arlete Matos 《International journal of environmental analytical chemistry》2013,93(3):189-197
Considering the importance of alkaloids in tobacco smoke, their presence was evaluated in real work environments. Sampling was carried out with fixed pumps and eventual degradation of the alkaloids during collection and storage until analysis was tested. A quantification method with an alternative internal standard (quinaldine) was evaluated and proposed. Offices and leisure rooms with high smoking intensity were chosen in order to detect minor alkaloids. The correlation between the environmental tobacco smoke markers - nicotine, 3-ethenylpyridine and myosmine - and the minor compounds was evaluated and all R2 were higher than 0.538. Nicotine levels quantified in the office rooms ranged from 0.02 to 64.67pg/m3 and a maximum of 129.33pg/m3 was found in one leisure room with very high smoking intensity. Myosnline and nicotyrine were the most abundant minor alkaloids and very high contents were. quantified in the leisure room mentioned previously. 相似文献
18.
Georgi H. Dobrikov Georgi M. Dobrikov Mariya Aleksandrova 《Central European Journal of Chemistry》2011,9(6):1126-1132
Two new low-molecular weight compounds — (Z)-4-(4-(dimethylamino)benzylidene)-1-(9-ethyl-9H-carbazol-3-yl)-2-phenyl-1H-imidazol-5(4H)-one and 2-(6-hydroxyhexyl)-6-(pyrrolidin-1-yl)-1H-benzo[de]isoquinoline-1,3(2H)-dione) — with possible application in organic light-emitting devices were synthesized. Their photophysical properties in
solution and in polymer films were investigated. The determined relative fluorescence quantum yields in solution for both
compounds were 0.003 and 0.51, while those in poly(methyl methacrylate) films were around 0.10 and 1.0, respectively. For
1H-imidazol-5(4H)-one derivative, single-layer organic displays with one emitting layer were prepared by spin-coating technology. The applied
voltage was 40 V (AC) with 1–3 KHz frequency. The emission maximum of the experimental AC display structures was at 600–630
nm. For displays with 2-(6-hydroxyhexyl)-6-(pyrrolidin-1-yl)-1H-benzo[de]isoquinoline-1,3(2H)-dione) the applied voltage was 60 V (AC) with 6-9 KHz frequency, but its future success will require more appropriate binding
polymers. Based on the obtained experimental results, it is concluded that the investigated compounds could be applied for
preparation of color electroluminescent structures.
相似文献
19.
20.
A. N. Shaikh R. N. Khandekar S. J. S. Anand U. C. Mishra 《Journal of Radioanalytical and Nuclear Chemistry》1992,163(2):349-353
Toxic trace metals like mercury, arsenic and cadmium have been determined in widely used Indian chewing tobacco and cigarette tobacco by neutron activation followed by sequential radiochemical separation (RNAA). Differential Pulse Anodic Stripping Voltammetry (DPASV) has been used for the estimation of lead, cadmium and copper in cigarette tobacco and its smoke aerosols. The reliability of the data has been assured by analyzing standard reference materials, bovine liver (NBS-1577) and orchard leaves (NBS-1571), and intercomparison of the Pb, Cd and Cu values by three techniques, namely, RNAA, DPASV and Energy Dispersive X-ray Flourescence technique (EDXRF). The levels of Hg, Cd, As, Pb and Cu in cigarette and chewing tobacco and the estimated intake of Cd, Cu and Pb to the smoker are presented and discussed. 相似文献