University of North Florida
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Contact Info

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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Telis Dimitrakopoulos

Abbrev:
Dimitrakopoulos, T.
Other Names:
Address:
Cardiff School of Engineering, PO Box 689, Cardiff CF2 3TF, UK
Phone:
NA
Fax:
NA

Citations 4

"Evaluation Of Perchlorate Tolerant Photo-cured Calcium-selective Electrodes For Use In Flow Injection Potentiometry"
Talanta 1997 Volume 44, Issue 3 Pages 349-356
Lucy Tina Di Benedetto, Telis Dimitrakopoulos*, John R. Farrell and Peter J. Iles

Abstract: The electrode slope and sensitivity of the photo-cured Ca ISE described by Dimitrakopoulos et al. (Electroanal., 1996, 8, 391) were improved by dissolution of anhydrous CaCl2 into the membrane prior to curing. The membrane composition was as follows; 44.7% Ebcryl 600 (bisphenol A epoxyacrylate), 22.3% 1,6-hexanediol diacrylate, 5.3% Uvecryl P36 (copolymerizable benzophenone photoinitiator), 20.8% dioctyl phenylphosphonate, 5.9% calcium bis-[4-(1',1',3',3'-tetramethylbutyl)phenyl] phosphate ionophore, 0.5% potassium tetrakis(4-chlorphenyl) borate and 0.5% CaCl2. Measurements were made vs. Ag/AgCl/saturated KCl//10% KNO3. The detection limit was 1 µM-Ca2+ and the calibration graph was linear for 0.01-100 mM. The ISE also showed an improvement in selectivity over interfering divalent ions and a wider pH range. It was suitable for the determination of Ca in the presence of perchlorate by flow injection potentiometry. Calibration graphs were linear for 0.01-10 mM Ca in 100 mM NaCl and the sample throughput was 150 injections per h at a flow rate of 1.5 ml/min. The method was applied to HNO3/HClO4 digests of milk. Results agreed with those obtained by AAS.
Calcium(2+) Milk Potentiometry Electrode Electrode Electrode Sample preparation Method comparison Selectivity Interferences

"Evaluation Of A Four Sensor Array Used In A Wall-jet Configured Flow Cell For Plow Injection Potentiometry"
Electroanalysis 2001 Volume 13, Issue 2 Pages 161-163
Lucy Tina Dimitrakopoulos, Telis Dimitrakopoulos

Abstract: Photo-cured calcium, potassium, and nitrate ion-selective electrodes and Ag/AgCl wire as a chloride electrode have been integrated into a sensor array that is suitable for FIP measurements in a wall-jet flow cell. Each sensor in the electrode-array exhibited near-Nemstian response over a log-linear range between 0.1 mM and 10 mM and detection limits of 0.01 mM in the flow injection potentiometric mode. The four coated wire electrodes were used simultaneously in the flow injection mode to determine their respective determinand in various water samples and the results were in good agreement with standard analytical methods.
pH

"Evaluation Of A New Wall-jet Flow-through Cell For Commercial Ion-selective Electrodes In Flow Injection Potentiometry"
Electroanalysis 1997 Volume 9, Issue 2 Pages 179-182
Lucy Tina Di Benedetto, Telis Dimitrakopoulos*

Abstract: The cited poly(methyl methacrylate) cell (28 x 25 x 35 mm) which can accommodate commercial gas-sensing, liquid polymer membrane and solid-state-based ISE is described (diagram given). The cell contains a 1 mm i.d. Ag/AgCl wire reference electrode and the dead volume of the ISE compartment is 18 µL. Two separate inlets and flow channels are used to carry the sample and reference solutions to the ISE and reference electrode, respectively, after which the streams are merged and carried to waste. The analysis rate was up to 240 samples/h and injection volumes >=50 µL are recommended. An Orion 95-12 ammonia ISE was used in the cell with a sample injection volume of 100 µL and 1 M KOH/1 µM-NH4Cl and 1 M KCl as carrier and reference solutions, respectively, e.g., at total flow rate of 1.8 ml/min. Calibration graphs of potential vs. log. NH3 concentration were linear for 0.1-10 mM NH3 and peak height RSD were 0.4-3.5%. The flow cell was also used to determine Ca and iodide using appropriate ISE.
Ammonium Calcium(2+) Iodide Potentiometry Electrode Electrode Flowcell Apparatus

"A Photocured Calcium Ion-selective Electrode For Use In Flow Injection Potentiometry That Tolerates High Perchlorate Levels"
Electroanalysis 1996 Volume 8, Issue 4 Pages 391-395
Telis Dimitrakopoulos*, John R. Farrell, Peter J. Iles

Abstract: A poly(methylmethacrylate) [PMMA] wall-jet electrode flow cell (2 µL dead volume) accommodating a commercial PMMA ISE (12 mm diameter) with an embedded Cu disk (6 mm diameter) coated with a Ca selective photo-cured membrane (preparation described) based on the calcium bis[4-(1,1,3,3-tetramethylbutyl)phenyl]phosphate ionophore and a lipophilic additive, potassium tetrakis(p-chlorophenyl) borate. Carrier and reference streams of 0.1 M NaCl were pumped (1.5 ml/min) through the flow cell and over a Ag/AgCl reference electrode with potentiometric detection. A 100 µL sample was injected into the carrier stream manually. Calibration plots (E/mV) exhibited log-linearity for 0.01-10 mM Ca(II) in CaCl2, which was unchanged in a 0.01 M NaCl/0.01 M NaClO4 (9:1) or 0.1 M NaClO4. The detection limit was 1 µM-Ca(II). The photo-cured electrode was satisfactory for Ca(II) measurements in the presence of high perchlorate levels and was used to measure total Ca(II) in full-cream milk. Results were in good agreement with those obtained by AAS.
Calcium Milk Electrode Potentiometry Method comparison