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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Patricia I. Ortiz

Abbrev:
Ortiz, P.I.
Other Names:
Patricia Inés Ortiz
Address:
Departamento de Fisicoquimica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba-Ciudad Universitaria, 5000 Cordoba, Argentina
Phone:
NA
Fax:
NA

Citations 5

"Characterization And Application Of Humic Acid Modified Carbon Electrodes"
Talanta 2003 Volume 61, Issue 4 Pages 547-556
Carlos D. García and Patricia I. Ortiz

Abstract: Four routes for the modification of carbon electrodes with humic acids and the determination of three divalent metallic cations were studied. The determination of bound Fe2+, Cu2+ and Ni2+ was performed by cyclic and square wave voltammetry using either a batch or flow analysis system. Using the FIA system and SWV, linear relationships between the oxidation (or reduction) current and the cations concentration were obtained with the modified electrodes, while no signals were obtained for the same conditions for bare carbon electrodes. The system can be used to study the interaction between a wide range of electroactive cations and humic substances; however, the performance as an analytical tool is limited due to the high limits of detection (µM). However, some advantages like simplicity, short analysis time, inexpensive instrumentation needs and miniaturization capabilities are remarkable.

"BHA And TBHQ Quantification In Cosmetic Samples"
Electroanalysis 2000 Volume 12, Issue 13 Pages 1074-1076
Carlos Diego García, Patricia Inés Ortiz

Abstract: An amperometric flow injection method for the determination of the antioxidants BHA, TBHQ and a mixture of them, using a 4-hydroxybenzaldehyde/formaldehyde polymer modified electrode is proposed. The procedure is based on the electrochemical oxidation in phosphate buffer solution (pH 7.2). Different analytical parameters and electrode stability were analyzed to obtain the best electrode performance, being the optimal conditions: working potentials 0.200 V and 0.700 V and flow rate 0.74 mL min-1. The proposed method was used for antioxidants quantification in a cosmetic sun tanning lotion, without any previous sample treatment and mean recoveries of 104% were obtained. Interferences from other antioxidants (BHT and PG) were also analyzed and in all the cases, no synergic behavior was observed.

"Determination Of Tert-butylhydroxytoluene By Flow Injection Analysis At Polymer Modified Glassy Carbon Electrodes"
Electroanalysis 1998 Volume 10, Issue 12 Pages 832-835
C.D. Garcia, P.I Ortiz*

Abstract: A flow injection method for the determination of the antioxidant BHT using polymer modified electrodes in connection with amperometric detection is proposed. The procedure is based on the electrochemical oxidation at 0.700 V (vs. Ag/AgCl [3 M NaCl]) in phosphate buffer solution (pH 7.2). BHT is determined over the range 0.001-0.020 or 0.005-0.030 g/L. Other analysis parameters, such as electrode working potential, flow rate, electrodeposited charge, and solution pH were optimized. The proposed method was applied to the determination of BHT in electrical transformer and vegetable oils samples. The results were compared with the HPLC-UV detection standard technique.
tert-Butylhydroxytoluene Oil Oil Electrode Electrode Amperometry Optimization Method comparison

"Electrochemical Determination Of Minoxidil In Different Pharmaceutical Formulations By Flow Injection Analysis"
Anal. Sci. 2006 Volume 22, Issue 1 Pages 91-94
Valeria Pfaffen And Patricia I. Ortiz

Abstract: The electrochemical behavior and amperometric-FIA quantification of minoxidil at a glassy carbon electrode is described. The procedure is based on electrochemical oxidation at 0.800 V (vs. Ag/AgCl/NaCl(3 M) in a phosphate buffer solution. Minoxidil was determined over the range 1 x 10^-7 - 1 x 10^-4 M. Different analytical parameters and electrode stability were analyzed to obtain the best electrode performance. The optimal conditions were: working potentials, 0.800 V; flow rate, 0.74 mL min-1; and solution pH 7.0. This system allowed a sampling rate of 120 samples per hour without any pretreatment. The proposed method was used for minoxidil quantification in pharmaceutical preparations with satisfactory results. The accuracy of FIA-amperometric method was established by a comparison with the conventional UV determination technique using a paired t-test indicating the absence of systematic errors.
Minoxidil Pharmaceutical Amperometry Electrode Method comparison

"Glassy Carbon Electrodes Modified With Different Electropolymerized Resol Prepolymer Mixtures For Phenol And Derivatives Quantification"
Anal. Sci. 1999 Volume 15, Issue 5 Pages 461-465
Carlos D. Garcia And Patricia I. Ortiz

Abstract: Phenol-formaldehyde mixtures are widely used in a variety of applications, such as flame-retardant or adhesives. This kind of resin can also be used as surface protecting polymers for glassy carbon electrodes when they are applied to phenol oxidative processes. The purpose of this work was to obtain the best conditions for phenol (and two derivatives) determination with a phenol-formaldehyde modified glassy carbon electrode in flow injection analysis (FIA) with amperometric detection and to compare these results with those obtained with two different modifiers, 4-hydroxybenzaldehyde and 4-hydroxybenzoic acid, under the same conditions. Linear relationships were obtained in the 0.1 to 1.0 µM phenol (or derivative) concentration range, the optima experimental conditions being 1.11 mL min-1, 0.700 V (vs. Ag/AgCl/NaCl 3 M), with an electrodeposited charge of the modifier of 1.10 C cm-2 and using an aqueous buffer (0.10 M total phosphate+0.05 M KCl, pH=7.0) as carrier solution.