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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Harry B. Mark

Abbrev:
Mark, H.B.
Other Names:
Harry B. Mark Jr.
Address:
Department of Chemistry, University of Cincinnati, P.O. Box 210172, Cincinnati, OH 45221-0172, USA
Phone:
NA
Fax:
+513-556-9239

Citations 11

"Development Of Sensors Based On Conducting Organic Polymer Electrodes"
Proc. Electrochem. Soc. 1999 Volume 23, Issue 1 Pages 104-112
Mark, H.B., Jr.;Rubinson, J.F.

Abstract: A review with 48 references. Electrodes modified by the electrodeposition of conducting organic polymers such as poly(3-methylthiophene), polypyrrole, polyaniline and polyphenylene exhibit remarkable electrocatalysis of the oxidation of catechol, catecholamine neurotransmitters, and other organic molecules of biological importance. Also, these organic electrode surfaces do not exhibit the fouling problems always observed on traditional metal and carbon electrodes. The electrocatalytic characteristics of these polymer electrodes were used to design amperometric detectors for the flow injection analysis (FIA) and high performance liquid chromatography (HPLC) determination of such species. The same electrodes can be employed in a potentiometric mode for the FIA and HPLC determination of inorganic and organic anions which are themselves electroinactive.
Review

"The Application Of Various Immobilized Crown Ether Platinum-modified Electrodes As Potentiometric And Amperometric Detectors For Flow Injection Analyses Of Catechol And Catecholamines"
Electroanalysis 1995 Volume 7, Issue 5 Pages 420-424
Suzanne K. Lunstord, Yi-Long Ma, Ahmed Galal, Cynthia Striley, Hans Zimmer, Harry B. Mark Jr.

Abstract: The crown ethers were polymerized onto a 2 mm diameter Pt disc electrode. The monomer solution comprised 0.025 M crown ether and 0.20 M tetrabutylammoniumtetrafluoriborate as supporting electrolyte in acetonitrile. Amperometric measurements were performed with a BAS model MF-1021 flow cell. Static potentiometric and potentiometric FIA measurements were performed with the polymer-modified electrode PTFE block incorporated into a standard BAS thin-layer flow cell with a Ag/AgCl electrode as second electrode. Measurements were performed with an Orion model 601A ionanalyzer. The potentiometric FIA response of all the crown ethers was linear over the range 10 mM to 10 µM. The lowest detection limits were 0.5 µmM for the potentiometric FIA with minimum interference from ascorbic acid, uric acid and acetaminophen. Detection limits for amperometric FIA was 5 µmM but there was significant interference from ascorbic acid, uric acid and acetaminophen.
Catechol, derivatives Catecholamine, derivatives Amperometry Electrode Electrode Potentiometry Crown ether Complexation Interferences

"Flow Injection Amperometric Detection Of Catechol Using Dual-band Poly(3-methylthiophene) Electrodes"
Electrochim. Acta 1998 Volume 43, Issue 23 Pages 3511-3524
Zhang Hong, Ahmed Galal, Judith F. Rubinson, Isam Marawi, Thomas H. Ridgway, Suzanne K. Lunsford, Hans Zimmer and Harry B. Mark Jr.*

Abstract: This work reports the electrochemical detection of catechol (10^-4 to 10^-6 M) in the presence of ascorbic acid (10^-4 to 10^-6 M) using dual-band poly(3-methylthiophene) (P3MT) electrode flow injection amperometry without prior separation The selectivity involved in this method is based on the differences in electrochemical behavior of catechol and ascorbic acid. A variety of dual-band Pt, Au, glassy carbon, and P3MT electrodes were constructed and used as the electrochemical detector. The upstream electrode of the series dual-band electrode unit was used for detection of catechol and ascorbic acid and the downstream electrode for detection of the oxidized catechol. The band dimensions range from 0.1 x 2.5 to 1 x 5.5 mm with the interelectrode gaps varying from 0.1 to 0.5 mm. Although this method is effective for dilute solutions of catechol (<10-5 M) in the presence of ascorbic acid (<10-5 M) under both neutral and acidic conditions, it is not efficient for more concentrated mixtures (>10-5 M) unless the measurements are made under acidic conditions such as at pH 1.6. A negative deviation from the ideal calibration curve of the oxidized catechol reduction is found in the more concentrated mixtures (>10-5 M) at physiological pH 7.4. Charge-dipole interaction and hydrogen bonding between the oxidized products of catechol and ascorbic acid in the concentrated neutral solutions probably explain the suppression of the current signals. Variation of the flow rates from 0.5 to 3.0 mL/min has no effect on the performance of the detector. The dual-band P3MT electrode has less positive oxidation potentials for catechol and ascorbic acid oxidation compared to the bare Pt, Au, and glassy carbon electrodes because of the catalytic activity of the P3MT electrode surface. Dual-band P3MT as well as glassy carbon electrodes have the best (highest) collection efficiency for catechol detection. The collection efficiency also remains constant when the interelectrode gaps vary from 0.1 to 0.5 mm.
Catechol Amperometry Electrode Apparatus Detector

"Electrochemistry And Detection Of Some Organic And Biological Molecules At Conducting Poly(3-methylthiophene) Electrodes"
Biosens. Bioelectron. 1991 Volume 6, Issue 4 Pages 333-341
Nada F. Atta, Ahmed Galal, A. Ersin Karag&ouml;zler, George C. Russell, Hans Zimmer and Harry B. Mark, Jr*

Abstract: Electrodes modified by the electrodeposition of poly(3-methylthiophene) were used as chemical sensors for some organic and biological molecules of industrial and medicinal interest. The electrochemical behaviors of ferri/ferrocyanide, catechol, ascorbic acid, hydroquinone, dopamine, epinephrine, acetaminophen, p-aminophenol and NADH were examined by cyclic voltammetry. The results showed that the proposed modified surface catalyzes the oxidation of these compounds. Differential pulse and square wave techniques were used for the analysis of binary mixture of ascorbic acid with catechol, NADH, dopamine and p-aminophenol. Voltammetric peak resolution was also demonstrated for a ternary mixture of ascorbic acid, catechol and p-aminophenol. Polymer coated electrode was also used in an amperometric detector for flow injection analysis of most of the aforementioned compounds. The responses of the polymer electrode were 4-10 times larger as compared to those of platinum. The modified electrode displayed excellent response stability for successive injections and detection limits were 10 ppb for catechol, dopamine, epinephrine, NADH and p-aminophenol, 1 ppb for acetaminophen and 100 ppb for ascorbic acid. Voltammetric peak positions were affected by the nature of the electrolyte and its pH. Also, film thicknesses were shown to be a factor affecting both the current magnitudes and oxidation peak potential of NADH.
Acetaminophen Ascorbic acid Catechol Dopamine Epinephrine Ferricyanide Ferrocyanide Hydroquinone Nicotinamide adenine dinucleotide oxidized 4-Aminophenol Amperometry Amperometry Electrode Voltammetry Sensor Catalysis pH PPB

"The Electrochemistry Of Neurotransmitters At Conducting Organic Polymer Electrodes Electrocatalysis And Analytical Applications"
Bioelectrochem. Bioenerg. 1995 Volume 38, Issue 2 Pages 229-245
Harry B. Mark, Jr., N. Attaa, Y. L. Ma, K. L. Petticrew, H. Zimmer, Y. Shia, S. K. Lunsford, J. F. Rubinson and Ahmed Galal

Abstract: The electrooxidation of catechols, catecholamines and NADH at conventional electrode materials is generally characterized by high degrees of irreversibility as well as strong adsorption and, hence, fouling by reactants and/or products of the reactions. On the contrary, the rates of the electron transfer are highly catalyzed by the use of conducting polymer films, such as poly(3-methylthiophene), polyphenylene, polyanaline and polypyrrole, as described here. Furthermore, the usual fouling problems are eliminated. Even interference from electroinactive large proteins, such as haemoglobin, and other surfactants are substantially reduced. Also, electron spectroscopy for chemical analysis, energy-dispersive analysis of X-rays, theoretical diffusion coefficient calculations, metal ion coordination, solution diffusion analyzes of cyclic voltammograms etc. show that the electron transfer occurs at the polymer-solution interface and not at the inert electrode substrate surface after diffusion through the polymer matrix or through pores. The analytical application of these polymer electrodes as amperometric detectors for flow injection analysis and high performance liquid chromatography are given. In addition, selective potentiometric electrodes for catecholamines based on conducting polymer films of crown ethers, such as binaphthyl-20-crown-6, dibenzo-18-crown-6, etc., have been developed and characterized. These potentiometric detectors significantly decrease the usual interferences of ascorbic acid, uric acid and acetaminophen found in amperometric detection. (60 References)
Catecholamines Amperometry Electrode Potentiometry Interferences Catalysis Diffusion coefficients Crown ether

"NMR-studies Of The Interaction Of Catechol And Ascorbic-acid With The Crown-ether"
Anal. Lett. 1996 Volume 29, Issue 8 Pages 1309-1318
Lunsford, S.K.;Striley, C.A.;Ma, Y.L.;Zimmer, H.;Kreishman, G.;Mark, H.B.

Abstract: Various crown ethers have been electropolymerized onto a platinum electrode for the determination of catechol and catecholamines by static potentiometry and potentiometric-flow injection analysis(FIA). The response mechanism of this modified electrode was investigated by scanning electron microscopy (SEM), electron dispersive X-ray analysis (EDAX), and electron spectroscopy for chemical analysis(ESCA). However, these studies were not conclusive with respect to possible mechanisms, and, therefore, nuclear magnetic resonance (NMR) studies were carried out on similar soluble crown ethers to determine the mode of interaction. As the crown ether resonances were shifted to higher fields by the added catechol in D2O but not d(6)-DMSO, it is postulated that the crown ether and catechol associate via interactions between hydrophobic surfaces. Hydrophilic ascorbic acid showed no NMR shifts which is consistent with its lack of potentiometric response. The EDAX and ESCA results indicated that then was also an interaction of catechol with the crown itself but the NMR shows that this interaction is a secondary effect in the overall electrode response. Several crown ethers were electropolymerized on to Pt electrodes for the determination of catechol and catecholamines by static potentiometry and flow injection potentiometry. The response mechanism of the resulting electrodes was investigated by scanning electron microscopy, electron dispersive X-ray analysis and electron spectroscopy for chemical analysis. These results were inconclusive and so 400 MHz 1H NMR Spectra were recorded with use of a Bruker AMX-400 MHz multinuclear spectrometer. NMR data indicated that crown ether aromatic rings and catechol rings were stacking on top of each other. Hydrophobic interaction seemed to be the major form of interaction which was confirmed by NMR studies in DMSO.
Ascorbic acid Catecholamines Catecholamine, derivatives Electrode Nuclear magnetic resonance Potentiometry Crown ether

"Determination Of Catechols In The Presence Of Ascorbic Acid And Uric Acid By Flow Injection Analysis Employing A Potentiometric Dibenzo-18-crown-6 Electrode Detector"
Anal. Lett. 1994 Volume 27, Issue 11 Pages 2141-2151
Lunsford, S.K.;Galal, A.;Akmal, N.;Ma, Y.L.;Zimmer, H.;Mark, H.B.

Abstract: A polished Pt disc electrode was modified by the electropolymerization of dibenzo-18-crown-6 (DB-18-C-6) on to its surface using an applied potential of +3.2 V (vs. Ag/AgCl) for 5 min in an electrolyte containing 0.025 M DB-18-C-6 and 200 mM tetrabutylammonium tetrafluoroborate. The modified electrode and a Ag/AgCl reference electrode were mounted in a thin-layer flow cell of a FIA system. The potentiometric response of the electrode to catechol and catecholamine was measured using a 20 µL injection loop and 0.1 M potassium phosphate buffer of pH 9.4 as the mobile phase (1 ml/min). The calibration graph was linear for 1 µM to 10 mM catechol and the detection limit was 0.5 µM. Similar results were obtained for the neurotransmitters. Interferences from ascorbic acid and uric acid were not significant until the concentration of the interferent exceeded a 10-fold excess.
Catechols Brain Electrode Electrode Potentiometry Interferences

"Composition Of 'copper(II)-poly(3-methylthiophene) Conducting Polymer' Electrodes"
Anal. Lett. 1994 Volume 27, Issue 7 Pages 1225-1237
Xue, Z.L.;Karagzler, A.E.;Zimmer, H.;Amer, A.;Ataman, O.;Mark, H.B.

Abstract: The electrode material formed by the chemical polymerization of 3-methylthiophene using Cu(II) salts as catalysts had previously been reported to be a poly(3-methylthiophene) incorporating co-ordinately bound Cu(II). The Cu-based substance was used as a working electrode in an amperometric detector for the detection of inorganic anions in flow injection mode. Its commercial viability made it important to elucidate the composition. The Cu-based material was analyzed by FTIR, XPS, elemental analysis and cyclic voltammetry. The material was a composite of Cu(I) and Cu(II) cations with cyano- and hydroxo-groups and some lattice or co-ordinated water molecules.
Copper(I) Copper(II) Environmental Spectrophotometry Voltammetry Electrode Amperometry

"Detection Of Hydrogen Peroxide At A Cadmium-modified Platinum Electrode In A Flow Injection Mode"
Anal. Lett. 1992 Volume 25, Issue 12 Pages 2175-2186
Akmal, N.;Mark, H.B.

Abstract: A polished Pt electrode (3 mm) was subjected to cyclic voltammetry from -0.1 to -1.0 V vs. Ag - AgCl in a solution of Cd(NO3)2 in 0.1 M KNO3 (pH 3) at 50 mV s-1 for 21 cycles. The electrode was mounted in a flow injection analysis assembly and used to detect H2O2 in a mobile phase (1 mL min-1) of 1 mM tricine solution, adjusted to pH 10.2. At -0.075 V vs. Ag - AgCl, the peak current response was ~3 x that of an unmodified Pt electrode. Calibration graphs were rectilinear for 1 to 9 nmol of H2O2 injected. The response of the electrode stored in air remained stable for 3 days. A polished platinum electrode has been modified using cyclic voltammetry in a solution of cadmium nitrate and supporting electrolyte. This Cd-modified electrode has been used for the detection of hydrogen peroxide in a flow injection mode. The electrodes modified in this manner showed electrocatalytic response for hydrogen peroxide at an applied potential of -0.075 V vs. Ag/AgCl, when compared to a bare platinum electrode.
Hydrogen peroxide Electrode Electrode Potentiometry

"Kinetic Determinations And Some Kinetic Aspects Of Analytical Chemistry"
Anal. Chem. 1984 Volume 56, Issue 5 Pages 96R-112R
Horacio A. Mottola and Harry B. Mark Jr.

Abstract: A review is presented, with 299 references, of the period November 1981 to November 1983. Sections are included on, inter alia, the determination of catalysts, kinetic methods based on inhibition or activation of catalysts, titrimetry with catalytic end-point indication, use of electrodes and luminescence, reaction rate methods, kinetics in separation and computerized instrumentation.
Kinetic Review

"Synergetic Effects In The Flow Injection Analysis Determination Of Catechol In The Presence Of Excess Ascorbic Acid By Series Dual-band Amperometric Detection"
Anal. Chim. Acta 1999 Volume 385, Issue 1-3 Pages 281-285
Harry B. Mark, Jr., Hong Zhang, Suzanne K. Lunsford, Ozcan Ceylan, Anthony I. Khaskelis, Nada Atta, Ahmed Galal, Sven Hausner, Judith F. Rubinson <i>et al.</i>

Abstract: The deviations at high concentrations (>10^-5 M) in the calibration curves for the determination of catechol in catechol/ ascorbic acid mixtures by flow injection analysis using series dual-band poly(3-methylthiophene)-coated electrodes has been re-examined, The cyclic voltammetry (at pH congruent to 7.4) of catechol/ascorbate and catechol/urate mixtures and NMR measurements show these deviations are the result of the simultaneous homogeneous catalytic reaction of dehydrocatechol with ascorbate.
Catechol Electrode Voltammetry Calibration Catalysis