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1.
Summary A gas chromatographic methodology with selective detection is presented for the analysis in wines and corks of pentachlorophenol residues, which are suspected to be the most likely precursors of some off-flavours described in several wine samples. After derivatisation, pentachlorophenol acetate residues were monitored by electrolytic conductivity detection and/or mass spectrometric detection in the selective ion mode at m/z 264 and 266. Recoveries varied from 80 to 96% for wine samples fortified with 5 to 100 g l–1 and from 83 to 91% for corks (fortified at 25 to 100 g kg–1). The proposed methodology allowed for a determination limit of g l–1 for wine and 10 g kg–1 for corks. 相似文献
2.
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
3.
A method for the fast routine analysis of the total content of volatile organic compounds in wallcoverings and paper products was developed, using headspace gas-chromatography for quantification. 57 wallcoverings of different types were investigated. Typical components were toluene, methyl-ethyl ketone, methyl-iso-butyl ketone, n-butyl acetate and iso-butyl acetate, all compounds being used as industrial solvents. The TVOC concentrations are calculated in toluene-carbon equivalents and ranged from 0.31 g/g to 1789 g/g with an average value of 123.22 g/g and a median of 20.37 g/g. To obtain an estimation of VOC-concentrations in indoor air, 10 selected wallcoverings were also analyzed in a 1 m3 climate test chamber. A correlation between headspace data and chamber concentrations could not be observed, which might be a result of increased analytical uncertainties at low emission rates under chamber conditions. 相似文献
4.
B. M. Dolgonosov 《Colloid Journal》2001,63(1):27-33
Kinetic equations were formulated, which describe coagulation–fragmentation process in a low concentrated suspension flow at a low shear rate. In such a system dispersed phase divided into fine and coarse fractions as the system is brought to equilibrium. Kinetic equations of two-fraction model were formulated. An approximate solution and, in one particular case, the exact solution of these equations were obtained for the equilibrium state. Detailed analysis of equilibrium particle distribution over the mass m was performed for an exponential coagulation kernel = 0
m
and an degenerated disintegration kernel = 12, in which the disintegration frequency is an exponential function of aggregate mass 1 = 0
m
+ , and the probability of the fragment detachment from an aggregate is independent ofm and decreases exponentially with an increase in mass of a fragment: 2 = 0
–1exp(–/0). The equilibrium distribution was shown to exist only at > 0, and in particular, it is described at = = 1 by the f() = 00
–1exp(–/0) and F(m) = Cx
–1(x + 1)2 – 1
e
–x
functions for the particles of fine and coarse fractions (x = m/m
0, = m
0/0, m
0 and 0 are the characteristic masses of coarse and fine fractions, respectively). The particle distribution for the fine fraction at 1 is well approximated by the Gaussian distribution exp[–(m – m
0)2/(4–1
m
00)]. 相似文献
5.
The absorption spectra of 4f electron transitions of the complexes of neodymium and erbium with 5,7-dibromo-8-hydroxyquinoline in the presence of octylphenol poly(ethyleneglycol)ether have been studied by normal and third-derivative spectrophotometry. The proposed method is free of interference of other rare earths. The calibration graphs were linear up to 18 g/ml of neodymium and 21 g/ml of erbium (in the final solution). The derivative molar absorptivities are 395 l.mol–1.cm–1 for neodymium and 3421.mol–1.cm–1 for erbium. The corresponding values of Sandell's sensitivity were 0.36 and 0.49 g.cm–1, respectively. The relative standard deviations evaluated from ten independent determinations of 2.5 g/ml of neodymium and erbium are 1.5 and 3.8% for neodymium and 1.8 and 4.1% for erbium in absence and presence of 70 g of lanthanum, respectively. The detection limits (signal to noise ratio=2) are 0.23 g/ml for neodymium and 0.30 g/ml for erbium. The method has been used for the determination of neodymium and erbium in mixed rare earths with satisfactory results. 相似文献
6.
N. Ramamoorthy M. K. Das B. R. Sarkar R. S. Mani 《Journal of Radioanalytical and Nuclear Chemistry》1986,98(1):121-126
Relatively longer liver technetium tracers such as95mTc (61 d) are useful for the development, evaluation and comparison of new technetium complexes for eventual development of99mTc radiopharmaceuticals. The feasibility of producing96Tc (4.35 d) and95mTc (61 d) was studied by the alpha bombardment of pure Nb targets (93Nb-100%).96Tc was obtained in a yield of 30 Ci/Ah using 16 MeV alphas, but it contained significant activity of95Tc (20 h) Relatively pure96Tc and95mTc was produced in yields of 18 Ci/Ah and about 1 Ci/Ah respectively with alphas of suitable energy and after allowing for suitable cooling periods after the end of bombardment (EOB). 相似文献
7.
A. Rosell J. O. Grimalt M. G. Rosell X. Guardino J. Albaigés 《Fresenius' Journal of Analytical Chemistry》1991,339(10):689-698
Summary The hydrocarbon composition of the particle and gas phases in the urban atmosphere has been studied by filtration and parallel adsorption on active charcoal and polyurethane foam (PUF). Gas chromatography (GC) and GC coupled to mass spectrometry (GC-MS) have been used for the analysis of the organic matter extracts obtained with each system. In the case of the particle and PUF samples these extracts were fractionated into aliphatic and aromatic compounds. This approach has allowed to identify up to 247 hydrocarbon molecules showing that C0–C5 alkylbenzenes are the major compounds in the charcoal extracts whereas C14–C23 n-alkanes, C0–C4 alkylnaphthalenes, C0–C4 alkylbiphenyls and C3–C5 alkylbenzenes are those predominantly found in the PUF materials. The particles essentially contain C17–C38 n-alkanes and parent polycyclic aromatic hydrocarbons (PAH). These qualitative differences are paralleled by a progressive concentration decrease from the more to the less volatile hydrocarbons. Thus, the total charcoal extracts average 80 g/m3, the PUF compounds represent 4 /m3 and the particle hydrocarbons 0.7 g/m3. These latter airborne materials are essentially composed of petrogenic residues 0.6 g/m3 (aliphatic fraction) whereas the pyrolytic PAH only involve 0.08 g/m3. 相似文献
8.
In a long-term field study at two locations with different air pollution levels several soot-selective measurement techniques were compared with a thermochemical method which measures non-extractable carbon (NEC) detecting the evolved CO2 by means of coulometric titration. The attenuation measurement technique (aethalometer) and the aerosol photoemission method showed good correlations to NEC for concentrations ranging from 1.6g/m3 to 40.8g/m3. The specific mass absorption coefficient of black carbon with respect to NEC varied between 8.4m2/g and 13.7m2/g with respect to the measurement sites, but the value was found to remain constant at each site independent of seasonal or meteorological variations. The ratio of photoelectric signal to NEC varied between 16 fA·(g/m3)–1 and 33 fA·(g/m3)–1 depending on the age of the aerosol. The diurnal variations of that ratio showed strong similarities to the traffic patterns. Additionally a slight temperature dependence of this ratio was found for the aged aerosol with a proportionality factor of – 0.35 fA·(K·g/m3)–1. With the reflectance measurement technique (smoke shade method) reliable NEC determination was not possible for NEC concentrations 5 g/m3. 相似文献
9.
A simple preparation of radionuclides of bismuth from lead thick targets bombarded by deuterons or protons consists in precipitation of solid lead nitrate in nitric acid /a minimum radiobismuth yield 98%/, coprecipitation of bismuth with lanthanum hydroxide and chromatographic isolation of carrier-free bismuth on a cation exchanger. The total yield of radiobismuth separation was not less than 85%. On bombardment with 20 MeV deuterons the yield is 20 Ci205Bi/Ah and 200 Ci206Bi/Ah. Mass distribution coefficients for bismuth were determined on the cation exchanger OSTION LG KS 0803 in dependence on the concentration of hydrochloric acid and nitric acid. 相似文献
10.
The optimum conditions for the extractive spectrophotometric determination of dioxouranium(VI) with hexamethyleneiminecarbodithioate(HMICdt) have been established. Dioxouranium(VI) reacts with this ligand at pH 4.5 to form a yellowish-orange uncharged 12 metal-ligand complex which can be extracted by chloroform. The calibration graph was linear in the range of 1–20 g ml–1 of dioxouranium(VI) at 335 nm. The molar absorptivity of the extracted species is 5.952×103 l mol–1 cm–1 with Sandell's sensitivity of 0.04 g cm–2. The average of 10 determinations of dioxouranium was 49.75 g for the samples containing 50 g of U(VI) and the variation from the mean at 95% confidence limit was 49.75±0.5955. 相似文献
11.
Yutaka Hayashibe Yasumasa Sayama Koichi Oguma 《Fresenius' Journal of Analytical Chemistry》1996,355(2):144-149
A computer-controlled flow injection system was developed for the determination of cadmium in a hydrometallurgical zinc refining process stream. An anion-exchange method in acidic potassium iodide medium was used for the on-line separation of cadmium from the matrix zinc. 1-(4-Nitrophenyl)-3-(4-phenylazophenyl)triazene (Cadion) was used as the chromogenic reagent for the spectrophotometric detection of cadmium. In order to expand the dynamic range of the flow injection - spectrophotometry, a computer-aided time-based variable-volume injection method has been employed for the introduction of the sample into the flow injection system. Samples ranging from 0.56 to 350 l can be delivered by controlling the time period of the sample introduction valve and the flow rate of the carrier solution. The system permits a throughput of 5 samples per hour. The reproducibility has been proven to be satisfactory with a relative standard deviation of less than 6.2% (sample injected: 0.56 l of 850 g Cd/ml; n=100) and 5.0% (350 l of 0.14 g Cd/ml; n=5). The determination limit was 20 g Cd/ml with 0.56 l sample injection and 0.05 g Cd/ml with 350 l sample injection (the absolute amount of cadmium injected into the system was 11 ng and 17.5 ng, respectively). 相似文献
12.
Neutron activation analysis is practically the only high-sensitivy element-selective detection method for chlorine, bromine and iodine. This method is just ideal for organic halogen determination after separation of organically bound species from inorganic. In recent years we have analysed organic chlorine and bromine from thousands of different kind of samples with different separation methods. For water samples we have used activated-carbon adsorption and for solid samples mostly propanone or combined alkaline/propanone extraction before activated-carbon adsorption. Inorganic chlorides were removed from the carbon by nitrate wash. The detection limits for total organic chlorine and bromine are 5 and 0.5 g/l for water (sample size 100 ml) and 0.3 and 0.1 g/g dry weight (sample size 1 g) for sediment. 相似文献
13.
Packed-column supercritical-fluid chromatography (pSFC) is presented as a novel method for separating and analyzing gramicidin samples. By use of methanol-modified carbon dioxide as a mobile phase the pentadecapeptides gramicidin A (gA), gramicidin B (gB), and gramicidin C (gC) are readily separated and eluted from a PRP-1 poly(styrene–divinylbenzene) column. Although optimum separation conditions are typically achieved near a column temperature of 40°C, a column pressure of 11 MPa, and 30% methanol modifier, pressure and modifier gradients around these values are also found to improve the overall separation time. Measurements indicate that the mobile phase solubility of gramicidin under these conditions is 5.0±0.4 g mL–1. Collection of individual peaks during chromatography achieved analytical-scale isolation of 2 g refined gC from 20 g injected gramicidin D. Further, supercritical-fluid extraction of 200 g gramicidin D from a Chromosorb 102 support packed into the vessel produced 57 g gA in 90% purity. The results establish that carbon dioxide-based mobile phases can be successfully used for the separation of individual gramicidin species. 相似文献
14.
Application of l-cysteine-capped nano-ZnS as a fluorescence probe for the determination of proteins 总被引:1,自引:0,他引:1
Zhu CQ Zhao DH Chen JL Li YX Wang le Y Wang L Zhou YY Zhuo SJ Wu YQ 《Analytical and bioanalytical chemistry》2004,378(3):811-815
Nanometer-sized l-cysteine-capped ZnS particles have been synthesized and used as a fluorescence probe to investigate the effect of proteins on fluorescent intensity. With =190 nm, maximum and constant synchronous fluorescence enhancement was produced at 267 nm and pH 5.12 in the presence of proteins. A highly sensitive synchronous fluorescence method for the rapid determination of proteins has been developed. Under optimum conditions, calibration graphs are linear over the range 0.03–8.0 g mL–1 for bovine serum albumin (BSA), 0.01–6.0 g mL–1 for human serum albumin (HSA), 0.05–8.0 g mL–1 for -globulin (-G), and 0.04–4.0 g mL–1 for ovalbumin, respectively. The relative standard deviations of seven replicate measurements were 1.75% for 1.0 g mL–1 BSA, 1.90% for 1.0 g mL–1 HSA, 1.65% for 1.0 g mL–1 -G, and 2.32% for 1.0 g mL–1 ovalbumin. 相似文献
15.
Reaction of Ru4(CO)13(3-PPh) (1) with the 1,3,5-hexatriyne Me3SiCCCCC CSiMe3 under mild thermal conditions affords initially Ru4(CO)10(-CO)2{4-1,1,2-P(Ph)C(CCSiMe3)C(CCSiMe3) (2), via the facile formation of a P–C bond in a manner similar to that demonstrated previously with alkynes and diynes. The 62-CVE cluster 2 readily decarbonylates to give crystallographically characterised Ru4(CO)10(-CO)(4-PPh){4-1,1,2,2-Me3SiCCC2CCSiMe3} (3). Attempts to further incorporate the pendant alkyne moieties in 3 into the Ru4 coordination environment were partially successful with Ru4(CO)10(4-PPh)(4-1,1,3,3-RC4R') (4, R/R'=SiMe3/CCSiMe3) being formed as a minor product together with the unusual toluene coordinated species Ru4(CO)7(6-C6H5Me)(4-PPh)(4-1,1,3,3-Me3SiC4CCSiMe4) (5). Cluster 3 reacts with an excess of Me3SiCCCCCCSiMe3 to give the open chain cluster Ru4(CO)9(3-PPh){4-2,2,4,4,-C4(CCSiMe3)(SiMe3)C4(CCSiMe3)3} (6). 相似文献
16.
M. Vobecký 《Journal of Radioanalytical and Nuclear Chemistry》1989,135(3):171-176
The interference contributions of uranium and thorium to the determination of cerium based on radionuclides141Ce and143Ce produced by irradiation in a reactor core was determined. The values of the interference contributions for141Ce were 0.28±0.01 g Ce/g U and /2.01±0.05/x10–3 g Ce/g Th, and for143Ce 1.33±0.03 g Ce/g U and /9.0±0.2/x10–3 g Ce/g Th. 相似文献
17.
The structure of the [Cu4(-Br)6(4-O)(ettz)4] complex of the monoclinic crystal system was investigated by X-ray diffraction analysis: a = 45.016(12), b = 9.363(4), c = 15.698(5) , = 100.28(2)°, V
cell = 6510(4) 3, space group C2/c, Z = 8,calc = 2.330 g/cm3, R1 = 0.0697 for 714 Fhkl 4 (F). The copper atoms form a tetrahedron with an oxygen atom in the middle and bromine atoms on the edges. The coordination polyhedron around the copper atom is a distorted trigonal bipyramid (CuOBr3N unit). All tetrazole ligands are monodentate and coordinated by the N4 atoms. 相似文献
18.
I. M. Fitsev G. K. Budnikov V. K. Blokhin P. G. Teslenko 《Journal of Analytical Chemistry》2003,58(8):755-761
The possibility of determining diacetylmorphine traces in various matrices by gas chromatography with mass spectrometric detection is demonstrated. Diacetylmorphine can be reliably determined by gas chromatography–mass spectrometry in the range 0.02–7.5 g/mL. A procedure is developed for the quantitative determination of diacetylmorphine and its concomitants, including acetylated opioid derivatives, in forensic samples. The detection limit for diacetylmorphine without preconcentration is 0.01 g/mL. The detection limit in the selective-ion monitoring mode with preconcentration is 1 × 10–4 g/mL. 相似文献
19.
Zusammenfassung Ein schnelles und einfaches Mikroverfahren zum Nachweis einiger Heteroatome organischer Verbindungen wurde entwickelt. Nach Aufschluß mit metallischem Kalium werden die entstehenden Ionen mit der Ringofenmethode getrennt und mit empfindlichen Reaktionen nachgewiesen. Nachweisgrenze: 0,5 bis 1g Stickstoff, 1 bis 2g Schwefel, 2 bis 3g Jod, 4 bis 5g Brom, 5 bis 10g Chlor in 0,5 bis 1 mg Einwaage.
Summary A rapid and simple micromethod was developed for the detection of several hetero-elements in organic compounds. After breaking down the sample with metallic potassium, the resulting ions are separated by the ring oven method and detected by means of sensitive reagents. Detection limits: 0.5 to 1g nitrogen, 1 to 2g sulfur, 2 to 3g iodine, 4 to 5g bromine, 5 to 10g chlorine in samples weighing 0.5 to 1 mg.
Résumé On a découvert un procédé à l'échelle micro, simple et rapide, pour rechercher certains hétéroéléments dans les composés organiques. Après mise en solution par le potassium métallique, on sépare les ions formés suivant la méthode du four annulaire et l'on effectue la recherche au moyen de réactions sensibles. Limite de dilution: 0,5 à 1g d'azote, 1 àg de soufre, 2 àg d'iode, 5 à 10g de chlore sur 0,5 à 1 mg de prise d'essai.相似文献
20.
Summary Chrome Azurol S permits a simple colorimetric determination of palladium with a sensitivity of 0.4g/cm2 (practical) or 0.04g/cm2
(Sandell), respectively. Conditions and interferences are described in detail.
Zusammenfassung Palladium läßt sich mit Hilfe von Chromazurol S auf einfache Weise kolorimetrisch bestimmen. Die praktische Empfindlichkeit der Methode beträgt 0,4g/cm2 bzw. 0,04g/cm2 nachSandell. Die Arbeitsbedingungen und die durch Fremdionen verursachten Störungen werden angegeben.
Résumé Le chromazurol S permet un dosage colorimétrique simple du palladium, avec une sensibilité de 0,4g/cm2 (en pratique) ou 0,04g/cm2 (Sandell) respectivement. On décrit en détail les conditions opératoires et les interférences.相似文献