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Determination of arsenic and selenium in spinach and tomato leaves reference materials using flow injection and atomic absorption spectrometry 总被引:1,自引:0,他引:1
A flow-injection atomic absorption spectrometric method was developed for the determination of trace amounts of arsenic and selenium in proposed spinach and tomato leaves standard reference materials (SRM 1570a and SRM 1573a). The samples were digested with HNO(3), H(2)SO(4) and HClO(4) using reflux column. The experimental details for sample preparation and the flow injection hydride generation method are discussed. The effect of matrix and various acid concentrations on the extraction and absorbance was also studied. The method has detection limits of 0. 15 ng As/ml and 0.17 ng Se/ml. Standard Reference Materials (SRM 1571 and 1547) were analyzed and the results agreed well with the certified values. 相似文献
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Chemical investigations of the fermentation broth from the microfungus Xylaria sp. have afforded the new natural product 3-chloro-4-hydroxyphenylacetamide 1 and the previously reported fungal metabolite 3-chloro-4-hydroxyphenylacetic acid 2. This letter reports the isolation and full spectroscopic characterisation of compounds 1 and 2 by NMR, UV, IR and MS data. The crystal structure and one-pot synthesis of 3-chloro-4-hydroxyphenylacetamide are also reported. 相似文献
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J.F. Watters 《代数通讯》2013,41(12):5951-5965
If R Vis a V-module and (R V W S) is a Morita context in which (S/WV) s is flat, then the trace ideal WVis left V-module over S. If, in additionS:(S/WV) is flat and S/WVis a fully left idempotent ring, then Sis also fully left idempotent. The lower (upper) Loewy length of R Vprovides an upper bound for the corresponding Loewy length of s(WV). 相似文献
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J. F. Watters 《Acta Mathematica Hungarica》1995,69(1-2):169-174
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A flow-injection analysis atomic absorption spectrometric (FIA-AAS) method was developed for the determination of trace amounts of arsenic, selenium and mercury in a proposed estuarine sediment standard reference material (SRM 1646a). The samples were prepared in two manners: a) A wet digestion procedure with HNO3, H2SO4, and HClO4 using a reflux column and b) A microwave-oven digestion procedure utilizing HNO3, H2SO4, and HCl for As and Se, and HNO3 for Hg. Microwave-oven digestion provides results comparable to those found by reflux column digestion and reduces the sample preparation time by a factor of 10. The proposed method employing the microwave-oven digestion procedure coupled with FIA-AAS for As and Se, and FIA-CVAAS for Hg, has detection limits of 0.15 ng As/ml, O.17 ng Se/ml and 0.15 ng Hg/ml.On leave from the Defense Metallurgical Research Laboratory, Hyderabad, India 相似文献
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A quantitative study by means of a glass pH electrode was made of the successive protonation of triethylenetramine(trien), in the pH range 2.0–12.0 at 25°C for unit ionic strength (KNO3). The successive acidity constants of fully protonated H4 trien4+ were found to be 10?3.97, 10?7.12, 10?9.49 and 10?10.14. 相似文献
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New definitions on reference materials 总被引:1,自引:0,他引:1
Hendrik Emons Ales Fajgelj Adriaan M. H. van der Veen Robert Watters 《Accreditation and quality assurance》2006,10(10):576-578
The new definitions for reference material and certified reference material as approved by ISO REMCO are provided and further explained. 相似文献