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101.
A systematic study of antimony reduction prior to its determination by hydride generation atomic fluorescence spectrometry (HG-AFS) was carried out. The efficiency of l-cysteine, potassium iodide and potassium iodide/ascorbic acid was studied for this purpose. The hydride generation step was optimised in the presence of those pre-reductors. From the results, l-cysteine was found to be the most suitable pre-reducing agent. Methodology was validated, obtaining detection limits lower than 90 ng l−1 and repeatability and reproducibility better than 3% R.S.D. and 5% R.S.D., respectively, in all cases. In order to evaluate the methodology developed and the influence of the matrix, recovery from waters from different sources was tested by HG-AFS and also by inductively coupled plasma mass spectrometry (ICP-MS). Accuracy was assessed by analysing three water reference materials at different antimony concentration levels. The high sensitivity of the developed methodology enables it to be applied for monitoring drinking waters according to the maximum admissible concentration of antimony established by the EU Directives. 相似文献
102.
I. M. Krukovskii M. S. Molchanova A. V. Evtushenko V. A. Shlyapochnikov 《Russian Chemical Bulletin》1998,47(7):1266-1273
The ratio between the numbers of structural formulas of C,H,N,O-containing energetic compounds belonging to the classes of
fuels (low values of the oxygen coefficientA), explosives (mediumA), and oxidants (highA values) was studied by a computer generation procedure. The number of the theoretically possible structural formulas was
found to decrease rapidly on going from fuels to explosives and then to oxidants; this observation agrees with the data on
the numbers of various energetic compounds currently used and proposed. The strategy of the search for new compounds with
the specified properties is described in brief, and its applicability to the search for explosives and oxidants with a small
(up to 12) number of atoms in a molecule is evaluated.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1304–1310, July, 1998. 相似文献
103.
The method of hydride generation atomic fluorescence spectrometry (HG-AFS) was optimised for determination of selenium in food supplements. Due to the high and varied content of Cu, Mg and Zn in the samples, the standard addition method was found to be the most appropriate. The reliability of the method was checked by the independent method of radiochemical neutron activation analysis, and good agreement was found between the two methods. HG-AFS is simple and rapid for Se determination in food supplements based on minerals. Agreement between the selenium values found and declared was worse than 10% in 9 out of 13 supplements. Furthermore, 2 of the 14 supplements did not comply with the recommendations stated in the 27th edition of the U.S. Pharmacopoeia, which states that minerals and vitamins in food supplements should be in the range of 90 and 200% of the declared value. 相似文献
104.
105.
Carmen Moscoso-Pérez Purificación López-Mahía Soledad Muniategui-Lorenzo Esther Fernández-Fernández Darío Prada-Rodríguez 《Analytica chimica acta》2004,526(2):185-192
A highly sensitive and simple method, based on hydride generation and atomic fluorescence detection, has been developed for the determination of As, Bi, Sb, Se(IV) and Te(IV) in aqua regia extracts from atmospheric particulate matter samples. Atmospheric particulates matter was collected on glass fiber filters using a medium volume sampler (PM1 particulate matter). Two-level factorial designs have been used to optimise the hydride generation atomic fluorescence spectrometry (HG-AFS) procedure. The effects of several parameters affecting the hydride generation efficiency (hydrochloric acid, sodium tetrahydroborate and potassium iodide concentrations and flow rates) have been evaluated using a Plackett-Burman experimental design. In addition, parameters affecting the hydride measurement (delay, analysis and memory times) have been also investigated. The significant parameters obtained (sodium tetrahydroborate concentration, sodium tetrahydroborate flow rate and analysis time for As; hydrochloric acid concentration and sodium tetrahydroborate flow rate for Se(IV); and sodium tetrahydroborate concentration and sodium tetrahydroborate flow rate for Te(IV)) have been optimized by using 2n + star central composite design. Hydrochloric acid concentration and sodium tetrahydroborate flow rate were the significant parameters obtained for Sb and Bi determination, respectively. Using a univariate approach these parameters were optimized. The accuracy of methods have been verified by using several certified reference materials: SRM 1648 (urban particulate matter) and SRM 1649a (urban dust). Detection limits in the range of 6 × 10−3 to 0.2 ng m−3 have been achieved. The developed methods were applied to several atmospheric particulate matter samples corresponding to A Coruña city (NW Spain). 相似文献
106.
107.
碱性体系在线氢化物发生—原子荧光光谱法测定痕量铋 总被引:4,自引:0,他引:4
提出了一种碱性体系在线氢化物发生-原子荧光光谱法测定痕量铋的分析方法。设计了在线氢化物发生系统流路及操作程序,研究了碱性体系氢化物发生的各项最佳条件。方法操作简便快速,能有效地消除过渡元素的严重化学干扰。应用于黄铜标样中痕量铋的直接测定,获得满意结果。 相似文献
108.
Biju Philip K. Sreekumar 《Journal of polymer science. Part A, Polymer chemistry》2002,40(16):2868-2877
A series of polyesters with π‐conjugated donor–acceptor segments was synthesized by the condensation of azobenzene‐4,4′‐dicarbonylchloride with 1,4:3,6‐dianhydro‐D‐sorbitol ([α] = + 42.5°) and biphenolic chromophores, bis(4‐hydroxyphenylazo)‐2,2′‐dinitrodiphenylmethane and bis(4‐hydroxyphenylazo)‐2,2′‐dinitrodiphenylsulfone. The polymers were characterized by spectral methods (IR, ultraviolet–visible, and NMR), thermal methods (thermogravimetry and differential scanning calorimetry), wide‐angle X‐ray scattering, and polarimetry. The polymers containing isosorbide units were optically active and crystalline. They exhibited glass‐transition temperature values between 100 and 160 °C and were stable up to 400 °C. The second‐harmonic generation (SHG) efficiency of the polymers was experimentally verified by a powder‐reflection technique with 2‐methyl‐4‐nitroaniline as a reference. The SHG efficiencies of the polymers were compared to those of the chromophores and explained as a function of the percentage of chiral composition. The hyperpolarizability β values were also determined by a two‐level model solvatochromic method and computational methods. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2868–2877, 2002 相似文献
109.
氢化物发生石墨炉原子吸收光谱法直接测定高温镍基合金中的硒 总被引:6,自引:1,他引:6
在6mol/L盐酸介质和0.1%KBH4条件下,不但能有效地发生硒的氢化物,而且5mg/mlNi和3mg/mlFe都不干扰硒的测定。利用涂钯石墨;管作为氢化物的原子化器,直接测定了高温镍基合金中的硒,特征质量为40pg,相对标准偏差在6.1%以内,回收率在97%-110%之间。 相似文献
110.
Inorganic arsenic was separated using the yeast-immobilized column. Saccharomyces cerevisiae was covalently bonded unto the controlled pore glass, which showed selective preconcentration of As5+ over As3+. The effluent was directly connected to hydride generation (HG) to increase sensitivity. The optimum pH condition for the retainment of arsenic at the column was 7. As5+ and As3+ were completely separated in a few minutes with the flow rate of 1.5 ml min−1. Three molars of nitric acid was adequate both for the elution of As5+ and hydride generation. The accuracy of the technique was tested with NIST SRMs. Quantitative analysis of arsenic species for herbicide, pesticide, and cigarette were performed, and the results showed good agreements with the suggested values. Yeast-immobilized column-HG-ICP showed a promising future for the arsenic speciation study. 相似文献