University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Frazier W. M. Nyasulu

Abbrev:
Nyasulu, F.W.M.
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Department of Pure and Applied Chemistry, University of Strathclyde, 295, Cathedral Street, Glasgow G1 1XL, U.K.
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Citations 3

"Potentiometric Monitoring Of Proteins. 6. Indirect Potentiometry"
Talanta 1993 Volume 40, Issue 9 Pages 1449-1459
Michael L. Hitchman and Frazier W. M. Nyasulu

Abstract: The indirect potentiometric determination of amino-acids and proteins with metal ions was used in both FIA and gel chromatography systems. In both applications a high purity Ag or Cu working electrode and double junction Ag/AgCl reference electrode was used with 0.5 M NaNO3 mobile phase (flow rate 23-60 ml/h) and 0.01-0.1 mM Cu2+. At 60 ml/min and 0.1 mM Cu2+ the calibration graph was rectilinear for 0.45 mM L-histidine and for 0.83 mM L-cysteine. This large linear range is explained in terms of a general model suggesting that a mechanism based on an electrode of the second kind was operating. The response indexes for a variety of proteins showed that the sensitivity was improved by lowering the mobile phase flow rate and by reducing the Cu2+ concentration.
Proteins Amino Acids Potentiometry Electrode Electrode Electrode Optimization Indirect

"Indirect Potentiometric Flow Injection Determination Of Silver In Photographic Fixing Solutions"
Anal. Chim. Acta 1989 Volume 220, Issue 1 Pages 287-291
Frazier Nyasulu

Abstract: Sample (0.4 ml) is injected into a stream of water that merges with a stream of 2 M H2SO4 at 70°C, and the SO2 produced is removed by diffusion through a 75-cm coil of Gore-Tex microporous PTFE tubing (pore size 3.5 µm). An excess of S2- in 6 M NaOH is added downstream of the coil, and the decrease in S2- concentration. is measured with a Ag - Ag2S electrode. The calibration graph is rectilinear from 1 mg L-1 to 10 g L-1 of Ag, and the detection limit is 0.04 mg l-1. Results for five fixing solution agreed well with those obtained by AAS.
Silver Fixing solution Potentiometry Electrode Diffusion Microporous membrane Goretex Method comparison Indirect

"Indirect Potentiometric Monitoring Of Proteins With A Copper Electrode"
Anal. Chim. Acta 1985 Volume 173, Issue 1 Pages 337-341
M. L. Hitchman and F. W. M. Nyasulu

Abstract: The electrode was a 0.25-mm diameter copper wire with only the tip exposed; it was mounted in a flow-cell that incorporated a double-junction silver - AgCl reference electrode and also a platinum-wire auxiliary electrode for cathodic pre-cleaning of the copper electrode. The protein was injected (injection volume 0.2 ml) into a carrier stream (1 mL min-1) of Cu(II) in 0.05 M phosphate buffer of pH 7.0; with 10 µM-Cu(II), proteins could be determined in the concentration. range 0.1 to 1 µM, the limits of detection for human albumin, bovine albumin, ovalbumin, phosvitin, human γ-globulin and catalase being 40, 90, 100, 30, 200 and 4 µg mL-1, respectively. Chloride only interferes when present at >0.01M, as compared with >10 µM in steady-state measurements. The system has been applied to proteins eluted from a size-exclusion column.
Proteins Ovalbumins Phosvitins Enzyme, catalase Globulins Albumin Human Blood SEC Electrode Potentiometry Interferences Indirect