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991.
三溴偶氮胂催化光度法测定痕量铁 总被引:19,自引:2,他引:19
本文研究了硫酸介质中痕量 Fe(Ⅲ)催化加速抗坏血酸、溴酸钾和三溴偶氮胂之间的褪色反应及动力学条件,建立了动力学光度法测定痕量Fe(Ⅲ)的新方法.方法灵敏度为1.82×10~(-12)g·ml~(-1).测定范围为Fe(Ⅲ)0~30ng/25ml.已用于人发和食品中痕量铁的测定.结果满意. 相似文献
992.
Assuming the separation of the intermolecular scattering function into the radial and angular parts and using Egelstaffet al’s orientational model for tetrachlorides, the structure of liquid vanadium tetrachloride has been studied. It has been observed
that such a separation is approximate for this liquid and the introduction of a third correction term is required to account
for the molecular structure function. The chlorine-chlorine partial structure and effective angleaveraged intermolecular chlorine-chlorine
potential in the liquid has been evaluated. Without taking the third correction term, introduced to generate theoretically
the molecular structure function, the centre structure function has been obtained in an approximate way from the experimentally
observed molecular structure function and from it the centre radial distribution function, centre direct correlation function
and the angle-averaged vanadium-vanadium effective potential has been evaluated. 相似文献
993.
J. Margitfalvi S. Gbölös E. Kwaysser M. Hegedüs F. Nagy L. Koltai 《Reaction Kinetics and Catalysis Letters》1984,24(3-4):315-321
The influence of rhenium on the behavior of a Pt/Al2O3 catalyst was studied in n-hexane reaction by means of dilution of the catalyst bed with Re/Al2O3. Parallel to activity, selectivity and ageing data obtained in slug pulse and continuous flow reactors, the amount of the surface carbon formed during the reaction was determined and its reactivity in hydrogen atmosphere was also studied. It is suggested that in the presence of rhenium due to the increase in the amount of hydrogen available for hydrogen consuming reactions including hydrodepolymerization of the carbonaceous surface overlayer, the routes of ageing processes are changed, resulting in lower carbon content on the catalyst and less pronounced catalyst deactivation.
Pt/Al2O3 -, Re/Al2O3. , , , , . , , , , , , , .相似文献
994.
Acceleration of CO hydrogenation by oxygen over palladium catalysts can be accounted for by competing reactions taking place in the CO-H2O2 system.
, CO O2 , CO–H2–O2.相似文献
995.
The sign of the charge-quadrupole moment product is shown to affect the rate of ion-linear quadrupole capture.
- .相似文献
996.
In solutions of 2:3-dimercaptopropanol an anodic polarographic wave, corresponding to the formation of an insoluble mercury-salt, was observed. Using this wave the reactions of 2:3-dimercaptopropanol with heavy metals and some oxidants were followed. Further anodic and cathodic polarographic waves formed were used for the identification of reaction products. Metals of the first analytical group form insoluble bidentate-chelate complexes, those of the arsenic-group soluble monodentate compounds. It was confirmed that after adding 2:3-dimercaptopropanol the metal-ions, bound to proteins, are set free. Most of the 2:3-dimercaptopropanol in a living body is inactivated by oxidation. Due to this fact it is necessary to use great doses of the 2:3-dimercaptopropanol in clinical treatments. Disulphide is formed in oxidation by H2O2 or cystine. Monothiolecompounds are also formed during the reaction with cystine. In solutions of p-benzoquinone no disulphide results. Both SH-groupings react by 1:4-addition with two molecules of quinone. 相似文献
997.
F. Ariese C. Gooijer N. H. Velthorst J. W. Hofstraat 《Fresenius' Journal of Analytical Chemistry》1991,339(10):722-724
Summary High-resolution fluorimetry in low-temperature n-alkane Shpol'skii matrices is a powerful technique for the analysis of rigid, non-polar compounds like polycyclic aromatic hydrocarbons. Because of the method's sensitivity and selectivity, sample clean-up, preconcentration and even chromatographic separation can often be left out. The Shpol'skii analysis of pyrene in crude extracts from marine sediments and from bird meat is demonstrated. Special attention is focussed on the extra possibilities acquired when a laser is used as excitation source (Laser Excited Shpol'skii Spectroscopy, LESS). 相似文献
998.
G. Vallebona G. Banchini A. Borraccini G. Raspi 《Fresenius' Journal of Analytical Chemistry》1988,331(6):584-587
Summary Surface active properties of dithizone and mercury(II) dithizonate have been analyzed by means of a laboratory apparatus for bubble extraction in view of utilizing it as a preconcentration device. Dependence of extraction efficiency on various parameters has been analyzed. Particularly, the dependence on concentration has been discussed in terms of adsorption isotherm and compared with that of a typical surface-active dye (crystal violet). It has been found that quantitative recovery ( 90%) of mercury, as mercury(II) dithizonate, is obtained from solutions of sufficiently low concentration ( 0.3 g/l).
Fraktionierextraktion als Anreicherungsstufe in der Spurenelementanalyse. Eine vorläufige Untersuchung相似文献
999.
N. A. Tyukavkina K. I. Lapteva V. A. Larina N. G. Devyatko 《Chemistry of Natural Compounds》1968,3(5):252-254
Summary The quantitative determination of quercetin and dihydroquercetin in the total flavonoids ofLatrix dahurica has been effected by the use of thin-layer chromatography on Kapron for separating the mixture with subsequent elution of the spots and colorimetry of the eluates obtained. The methanol-dimethylformamide (1:1) system was used as the eluate. It has been found that the flavonoids of the heartwood ofLatrix dahurica contain a predominating amount, 69% of dihydroquercetin, the amount of quercetin being 11%.Khimiya Prirodnykh Soedinenii, Vol. 3, No. 5, pp. 298–301, 1967 相似文献
1000.
An accurate and simple method has been developed for the determination of Pt, Ru, Ir and other elements employing instrumental neutron activation analysis (INAA). Nondestructive analysis has been carried out for the determination of these elements in different rock samples such as Dolerite, Dyke Dolerite, Country Basalt, Hyaloclastite, Trachyte, Ijolite, Spillite, Diorite and Lamprophyre from various locations like Daman, Tapti, Murud, Talasari, Ranala and Bassein in Maharashtra state. High flux provided by the CIRUS reactor (1×1013 n cm–2s–1) has been used for thermal neutron bombardment followed by radioassaying of the (n,) products on a HPGe detector coupled to a PC-based MCA unit. 相似文献