排序方式: 共有5条查询结果,搜索用时 15 毫秒
1
1.
Yallouz AV Calixto de Campos R Paciornik S 《Fresenius' Journal of Analytical Chemistry》2000,368(5):461-465
A non instrumental method for the semiquantitative determination of mercury in fish is described. The sample is acid digested and the mercury vapor released after chemical reduction with SnCl2. The mercury vapor is then collected on a detecting paper covered with an emulsion of Cu2I2, 3% carboxymethylcellulose and MgCl2 as moistener agent. The colored Cu2[HgI4] complex is formed and the color intensity is proportional to the mercury concentration in the original sample. Parameters such as sample mass/digestion solution volume ratio, emulsion composition, paper covering technique, carrier gas flow were investigated. Comparative studies using CVAAS and digital color analysis after scanning the papers confirmed the applicability of the method to real samples. 相似文献
2.
R Nirmala V Sankaranarayanan K Sethupathi AV Morozkin T Geethakumary Y Hariharan 《Pramana》2002,58(5-6):1101-1104
New R
2Ti3Ge4 (R=Dy, Ho and Er) intermetallic compounds have been synthesized and characterized by X-ray diffraction and low temperature ac
magnetic susceptibility, electrical resistivity and thermoelectric power measurements were carried out. The compounds crystallize
in the parent, Sm5Ge4-type orthorhombic structure (space group Pnma) and lanthanide contraction is observed as one moves along the rare-earth series.
The changeover from paramagnetic to antiferromagnetic phase happens at low temperatures and the ordering temperature scales
with the de Gennes factor. The electrical resistivity is metallic with a negative curvature above 100 K. Thermopower displays
a weak maximum at temperatures less than 50 K signifying the possible phonon and magnon drag effects. 相似文献
3.
A. V. Yallouz R. Calixto de Campos S. Paciornik 《Analytical and bioanalytical chemistry》2000,366(5):461-465
A non instrumental method for the semiquantitative determination of mercury in fish is described. The sample is acid digested
and the mercury vapor released after chemical reduction with SnCl2. The mercury vapor is then collected on a detecting paper covered with an emulsion of Cu2I2, 3% carboxymethylcellulose and MgCl2 as moistener agent. The colored Cu2[HgI4] complex is formed and the color intensity is proportional to the mercury concentration in the original sample. Parameters
such as sample mass/digestion solution volume ratio, emulsion composition, paper covering technique, carrier gas flow were
investigated. Comparative studies using CVAAS and digital color analysis after scanning the papers confirmed the applicability
of the method to real samples.
Received: 3 July 1999 / Revised: 29 September 1999 / Accepted: 21 October 1999 相似文献
4.
Resonant ultrasound spectroscopy was used to measure the elastic constants of bcc Ta0.33V0.67 over the temperature range 3.5–300?K; the results were compared to earlier measurements on C15 TaV2. The temperature dependence of the polycrystalline shear modulus is completely different in the two phases; that of the bcc phase decreases with temperature whereas that of the C15 phases increases in an anomalous fashion. This difference is consistent with a model involving doubly-degenerate levels at the X point of the Brillouin zone in the C15 phase with the Fermi level lying near the doubly degenerate level. This model accounted for the unusual behaviour of the C15 phase. Debye temperatures were determined from the ultrasonic measurements: 295?K for the C15 phase and 315?K for the bcc phase. 相似文献
5.
Three different analytical methods comprising colorimetric method with 1,5-diphenyl-carbazide, electrothermal atomic absorption spectrometry (ET AAS) and flame atomic absorption spectrometry were utilized in a study to determine traces of chromium (Cr) in synthetic tannery effluent from laboratory scale treatment process variations. All the results obtained using the three different methods showed good agreement and met the requirement of Brazilian regulation for total Cr for effluent discharges (<0.5 mg l(-1)). However, ET AAS has been the proposed method because it was faster, less laborious, needed smaller volume of sample and presented lower limit of quantification (LOQ=2.2 mug l(-1)). 相似文献
1