Vanadium complexes cupferron

R spectra, 2, 511 Vanadium tetramethoxide spectroscopy, 2, 347 Vanadyl acetylacetonate, 2, 388 hydrolysis, 2, 379 Vanadyl complexes cupferron... 

Determination of uranium with cupferron Discussion. Cupferron does not react with uranium(VI), but uranium(IV) is quantitatively precipitated. These facts are utilised in the separation of iron, vanadium, titanium, and zirconium from uranium(VI). After precipitation of these elements in acid solution with cupferron, the uranium in the filtrate is reduced to uranium(IV) by means of a Jones reductor and then precipitated with cupferron (thus separating it from aluminium, chromium, manganese, zinc, and phosphate). Ignition of the uranium(IV) cupferron complex affords U308. 

A method has been described108 for the vanadium(V) complexes with MeOH, utilizing the shift of the frequencies for the sym and asym vibrations of Me from 2835 and 2950 cm-1 in free MeOH to 2810 and 2910cm 1, respectively, in VO(OMe)L2 complexes, where HL = cupferron, 8-quinoli-nol, etc. The IR spectra of VO(OH)L2 complexes of the above two ligands have been recorded in this publication. 

The adsorptive inverse voltammetric determination of vanadium is a very sensitive method with detection limits of 0.2 fig/L After a complete wet oxidative digestion of the sample the VO2+ or VO3+ is oomplexed with cupferron by pH 8.5. The complex is adsorbed over a defined period at a hanging mercury drop (HMDE). Subsequently a potential range of -0.5 V to -0.95 V was applied in the differential pulse mode to measure the peak current at around -0.75 V, The quantitative determination was carried out by means of the method of standard addition using at least three additions. The precision in series is 6.4% at a concentration of 2.5 fig/L urine and the day to day precision 3.9% at a concentration of 5//g/L urine (Seiler, 1993). A detailed description of this sensitive method is given in the 4th volume of Analyses of Hazardous Substances in Biological Materials (Angerer and Schaller, 1993). 

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