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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Njegomir Radic

Abbrev:
Radic, N.
Other Names:
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Department of Chemistry and Environmental Chemistry, University of Split, Split 21000, Croatia
Phone:
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Citations 4

"Flow Injection Determination Of Compounds Containing Sulfur By Using Potentiometric Tubular Sensor"
Lab. Rob. Autom. 1998 Volume 10, Issue 3 Pages 143-149
Njegomir Radic*, Josipa Komljenovic

Abstract: A flow injection analysis (FIA) setup with flow-through tubular solid-state AgI-based membrane detector, sensitive to the sulfhydryl group, was examined Application of a flow injection system is exemplified by the determination of different compounds containing sulfur in 0.1 M HClO4 as a supporting electrolyte. For compounds with -SH group, a rectilinear calibration graph was obtained by plotting the peak height vs. concentration. of RSH. The experimental slope is in good agreement with the theoretical (59 mV/decade) value postulated on an precipitation process and formation of RSAg into the carrier stream or at the sensing part of the detector. The described FIA setup with used sensor can be applied for calculation of the solubility product of RSAg or stability constant of Ag(SR)n(1-n) complex.
Sulfur compounds Electrode Electrode Potentiometry Equilibrium constants

"Preparation Of An Ion-selective Electrode By Chemical Treatment Of Copper Wire For The Measurement Of Copper(II) And Iodide By Batch And Flow Injection Potentiometry"
Fresenius J. Anal. Chem. 1999 Volume 365, Issue 4 Pages 314-319
D. Dobcnik, M. Kolar, J. Komljenovic, Nj. Radic

Abstract: The preparation of an ion-selective electrode by chemical treatment of copper wire and its application for the measurements of copper (II) and iodide ions is described. The proposed reaction mechanism at the sensing surface, which explains the response of the electrode to Cu2+ and iodide ions, is discussed. The prepared electrode was suitable for direct potentiometric measurements of iodide and copper (II) in batch experiments down to concentrations of 1 x 10^-5 mol L-1. A tubular electrode, prepared in the same way, may be used as a potentiometric sensor in a flow injection analysis for Cu (II) and/or iodide determinations.

"Determination Of Penicillamine By Batch And Flow Injection Potentiometry With AgI-based Sensor"
Croat. Chem. Acta 2000 Volume 73, Issue 1 Pages 263-277
Njegomir Radic, Josipa Komljenovic, and Danilo Dobcnik

Abstract: Potentiometric determination of penicillamine (pen) is described based on a batch experiment and flow-injection analysis (FIA) using a chemical sensor with AgI-based membrane. The membrane was prepared by pressing silver salts (AgI, Ag2S) and powdered Teflon. This membrane was incorporated in a multipurpose electrode body for batch measurements, and in a tubular flow-through sensor body for FIA measurements. For batch measurements, the equilibrium potentials recorded with continuous addition of standard penicillamine solution were considered in relation to lg (c(pen)/mol L-1). Linear response with slope of 60 mV was obtained in the concentration range from 2.5 x 10^-5 mol L-1 to 1.8 x 10^-2 mol L-1. In using the tubular sensor with a membrane of the same composition for FIA measurements, the linear response with slope of 59 mV was recorded in the concentration range from 1 x 10^-4 mol L-1 to 1 x 10^-1 mol L-1. The response of the applied chemical sensor to penicillamine (designated also as RSH) is explained by the formation of sparingly soluble RSAg in the reaction solution and/or on the exposed surface of the sensor. The solubility product K-s(RSAg) was determined using experimental values recorded both by batch measurements and by the continuous-flow experiment. The mean value obtained by different measurements and using a membrane of the same composition is K-s(RSAg) = (1.4±0.1) x 10^-20 mol2 L-2.
Membrane

"Flow Injection Potentiometric Determination Of Fe(III) Using A Fluoride-selective Electrode As Detector"
Analusis 1999 Volume 27, Issue 1 Pages 57-60
M. Bralic and N. Radic

Abstract: Flow injection analysis (FIA) system incorporating a fluoride ion-selective electrode (FISE) as detector is described. Laboratory-built cascade flow cell equipped with FISE and reference electrode is used for flow injection potentiometric determination of Fe(III) based on monitoring of the formation of FeF2+ in acid solution. Under optimized flow conditions (4.0 mi, min-1, 300 µL samples, 10^-5 mol L-1 sodium fluoride in the carrier stream) a rectilinear calibration graph is obtained by plotting the peak height versus concentration of iron in the range of Fe(III) concentration from 1 x 10^-4 to 1 x 10^-1 L mol L-1 in a 0.01 mol L-1 perchloric acid or acetate buffers (pH 2.8; 3.4).