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51.
Determination of selenium, zinc and cadmium in antidandruff shampoos by atomic spectrometry after microwave assisted sample digestion 总被引:1,自引:0,他引:1
Microwave assisted pre-treatments for atomic spectrometric determination (inductive coupled plasma-optical emission spectrometry, ICP-OES or flame atomic absorption spectrometry, FAAS) of metallic elements, usually present in antidandruff shampoos, are proposed. They are based on the digestion of the sample with HNO3 into a closed reactor, which is irradiated at 800 W for a few minutes. Selenium was determined by ICP-OES. The limit of detection was 0.11 mg l−1; the relative standard deviation (R.S.D.) for the selenium content in the samples was in the 0.6–3.6% range. The results obtained were in agreement with the label contents and the recovery of the proposed method was in the 100–106% range. Zinc and cadmium were determined by FAAS. The limit of detection for zinc determination was 0.078 mg l−1; the R.S.D. for zinc contents was in the 0.8–8.6% range. A limit of detection of 0.09 mg l−1 was obtained for cadmium determination; the R.S.D. for cadmium contents was in the 0.7–2.7% range. The determinations were performed after two different sample mineralization pre-treatments — dry ashing (in an electric furnace) and wet mineralization (in a microwave oven). Both methodologies provided comparable results for zinc and cadmium determination in shampoos. The proposed microwave assisted digestion procedures allow a precise and accurate determination of selenium, zinc and cadmium in commercial antidandruff shampoos, and the sample pre-treatment is less time-consuming than the classic methods. 相似文献
52.
Sérgio L. C. Ferreira Neyla M. L. Araújo Adriana B. Santos Alailson F. Dantas A. C. Spinola Costa 《Mikrochimica acta》1995,118(1-2):123-129
TAN reacts with zinc(II) forming a red complex with composition 1:2 Zn(II)-TAN and absorption maximum at 582 nm. Zinc can be determined with this reagent in the presence of Triton X-100, in the pH range 6.20-8.00 with a molar absorptivity of 4.5×104 l/mol/cm Beer's Law was obeyed up to least 1.55 g/ml. Copper interference was eliminated with a mixture of thiosulfate and ascorbic acid and nickel separated by precipitation with dimethylglyoxime. The proposed method was used for zinc determination in several copper-base alloys and the results of analysis in comparison with certified values indicated that the procedure was accurate and precise. A derivative procedure is also proposed, allowing zinc determination with high sensitivity (5-400 ng/ml). 相似文献
53.
已证明小儿厌食症除与缺乏微量元素锌关系密切外,还与其他多种微量元素和宏量元素的缺乏或低下也有关。本院以自行研制的中药强壮灵冲剂治疗小儿厌食症疗效显著。其于浸膏粉经20余种微量元素测定表明含有锌、铁、钴、铜、镍、锰、铬、锗、锶、铝、钡、硒、硅、钛等多种人体必需且品种齐全,含量适度的微量元素。上述元素又恰是患儿体内所缺乏和低下的品种,无疑对患儿全面适度的补充大有裨益.中药强壮灵与西药硫酸锌临床对比研究表明,无论比发锌回升数值以及从厌食等全面疗效统计,中药组均明显优于西药组,并且发现疗效与药物的补锌量不成正相关。说明中药的调理脾胃功能及综合整体治疗作用是其突出优点,值得推广. 相似文献
54.
E. H. Mørkved 《Chemistry of Heterocyclic Compounds》2007,43(9):1197-1201
Syntheses and spectroscopic characteristics are reported for eight pyrazine-2,3-dicarbonitriles substituted with maleimide
residue in addition to phenyl, 2-thienyl, or 2-furyl substituent.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1409–1414, September, 2007. 相似文献
55.
Xiaoling Bao Jianhong Liu Qingshu Zheng Wei Pei Yimei Yang Yanyun Dai Tao Tu 《中国化学快报》1990,30(12):2266-2270
A novel protocol allowing convenient and highly selective visual recognition of melamine in raw milk via selective metallo-hydrogel formation at a concentration as low as 10 ppm without any tedious pretreatment has been developed. 相似文献
56.
1 INTRODUCTION Coordination chemistry has been playing an important role in nonlinear optical (NLO) materi- als [1~3] in recent years. It has been found that tetrahedral or square pyramidal molecular configurations are useful for designing transparent second-harmonic generation (SHG) materials from coordination compounds[4]. It has also been reported that the pyridyl-based metal complexes can exhibit SHG effects[5]. Recently, we have successfully synthesized a new coordination compoun… 相似文献
57.
银微电极微分电位溶出分析法研究 总被引:3,自引:1,他引:3
本文首次报道了银微电极微分电位溶出分析法。用化学刻蚀法方便地制作了银微电极,用于DPSA具有背景值低,分辨率好、精密度及灵敏度高,在不搅拌,仅需一定酸度而酸度而无其它介质的条件下就能测试等优点,对人工试样及自来水样分析,结果令人满意。 相似文献
58.
D. N. Dybtsev I. E. Sokolov E. V. Peresypkina V. P. Fedin 《Russian Chemical Bulletin》2007,56(2):225-230
Two new scaffold-like metal-organic coordination polymers, [Zn2ndc2bpe]·DMF and [Zn2ndc2dedpbp] ·4DMF (ndc is 2,6-naphthalenedicarboxylate, bpe is trans-bis(4-pyridyl)ethylene, and dedpbp is 4,4′-diethynyl-4″,4′″-dipyridylbiphenyl), were synthesized by heating stoichiometric
amounts of zinc(II) nitrate, H2ndc, and bpe or dedpbp in DMF. The structures of the polymers were established by X-ray diffraction. Coordination of linear
dicarboxylate ligands to zinc cations gives rise to planar square-grid networks, and additional coordination of the bifunctional
nitrogen-containing ligands results in the formation of scaffold-like triply interpenetrating structures with a primitive
cubic topology.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 219–223, February, 2007. 相似文献
59.
60.
合成了一系列以不同长度柔韧链相连的p/p型单核锌双卟啉配合物。选用Tripos力场,利用分子动力学模拟退火和分子力学构象搜索相结合的方法对该系列双卟啉进行了能量优化和构象分析。理论计算结果表明:该类双卟啉稳定存在的最低能量构象为叠合式,最高能量构象为伸展式,并存在一系列的中间能量构象;双卟啉分子内π-π作用和能量转移与双卟啉存在的两种主要构象密切相关;分析了分子内π-π作用的本质。运用不同光谱测试手段验证了理论计算结果: 利用可见和相应二阶导数吸收光谱研究了双卟啉主要存在的叠合式和伸展式构象,通过红外光谱观察了对双卟啉构象和卟啉环间π-π作用较为敏感的吸收谱带;利用荧光光谱计算了双卟啉的分子内能量转移效率。 相似文献