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Results for “POLAROGRAPHY”

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At least 217 records · Page 12Linked to original sources
PubMed2001

Determination of niobium in pyrochlore ore by differential pulse polarography.

A differential pulse polarographic method has been developed for the quantitative determination of niobium in pyrochlore ore. One-step polarographic curves were obtained in 0.01 mol L(-1) EDTA as supporting electrolyte. Analytical curves indicated that response was linearly dependent on Nb(V) concentration between 1.6 and 8.6 mg L(-1) in the pH range 2-5. The system is quasi-reversible and controlled by diffusion in 0.01 mol L(-1) EDTA as supporting electrolyte; the electrode process involves one-electron reduction of Nb(V) to Nb(IV). The results obtained so far for niobium in pyrochlore ore were comparable with those obtained by X-ray fluorescence determination. Ions such as Fe(III), Cr(III), As(III), Cu(II), Ni(II), Co(II), Mn(II), Sn(IV), Zn(II), V(V), Ta(V), W(VI), Ce(IV), and Ti(IV) did not interfere. Possible interference from Pb(II) can be avoided by complexation with the supporting electrolyte in the pH range 3.5 to 4.6; Mo(VI) ions can be tolerated when their concentration is one-tenth that of Nb(V).

Electrochemistry↗
PubMed1988

Monitoring spinal cord blood flow using hydrogen polarography.

Spinal cord blood flow (SCBF) is an important physiological variable that may undergo changes following cord injury. We measured SCBF in healthy dogs whose cord had been cooled, a technique that is useful for treating spinal cord injured patients. A microcomputerized system developed for efficient recording of SCBF on-line is described in this paper.

Animals↗
PubMed1979

Polarography and voltammetry in studies of toxic metals in man and his environment.

A brief introduction on sources, occurrence and fate of some toxic trace metals found in the natural environment is followed by a discussion of general methodological aspects from the trace chemical viewpoint. The versatile, significant and specific potentialities of advanced polarographic and voltammetric methods are compared with relevant non-electrochemical alternatives. They are subsequently demonstrated by a survey on representative applications, results and findings on problems from all types of environmental compartments and food chains to man, with emphasis on the toxic trace metals Cu, Cd, Hg, Pb, and also in certain matrices for Zn, As, Se, Tl and Bi. A final section is devoted to the particular potentialities of the electrochemical approach for speciation studies in natural waters at realistic trace levels of the dissolved toxic metals, e.g. Zn, Cd and Pb.

Chemical Phenomena↗
PubMed1995

Evaluation of the polarographic technique for assay of the viability of freeze-dried BCG vaccine: II. Viability of the vaccine assessed by polarography, Warburg respirometry and colony counting.

A comparative study of the viability of 34 lots of freeze-dried BCG vaccine has been carried out using an oxygen electrode polarographic technique, Warburg respirometry and colony counting. There were no statistical differences between the results obtained with the polarographic and Warburg techniques. Both methods gave reliable and similar results and showed a positive correlation (r = 0.8615). Comparison between the polarographic and colony-counting methods showed a positive correlation (r = 0.6530); for comparison between the Warburg and colony-counting methods, the correlation value was r = 0.6868. All the tests were significant at the level of alpha = 0.05. The advantages of the polarographic technique are that it is much less time- and material-consuming than other methods. It is a reliable, inexpensive and convenient method for BCG vaccine quality control.

BCG Vaccine↗