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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
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Bulletin of the Korean Chemical Society

  • Publisher:
  • FAD Code: BKCS
  • CODEN: BKCSDE
  • ISSN: 0253-2964
  • Abbreviation: Bull. Korean Chem. Soc.
  • DOI Prefix: 10.5012/bkcs
  • Language: English
  • Comments: Fulltext from 1980 V1

Citations 18

"Indirect Determination Of Nitrite By Flame Atomic Absorption Spectrometry Using A Lead(IV) Dioxide Oxidant Microcolumn"
Bull. Korean Chem. Soc. 2006 Volume 27, Issue 6 Pages 875-880
Meissam Noroozifar*, Mozhgan Khorasani-Motlagh, Aboozar Taheri, Marjan Homayoonfard

Abstract: A new, simple and fast flow injection analysis (FIA) method has been developed for the indirect determination of nitrite. The proposed indirect automatic method is based on the oxidation of nitrite to nitrate using a lead(IV) dioxide oxidant microcolumn where the flow of the sample through the microcolumn reduces the PbO2 solid phase reagent to Pb(II), which is measured by flame atomic absorption spectrometry. The absorbance of Pb(II) are proportional to the concentration of nitrite in the samples. The calibration curve was linear up to 30 mg L-1, with a detection limit of 0.11 mg L-1 for a 400 µL injected sample volume and a sampling rate of about 80 h-1. The results exhibit no interference from the presence of large amounts of ions. The developed procedure was found to be suitable for the determination of nitrite in foodstuffs and wastewaters. A relative standard deviation better than 0.9% was obtained in a repeatability study. The reliability of the method was established by parallel determination against the standard method.

"Synthesis Of Novel Electrochemiluminescent Polyamine Dendrimers Functionalized With Polypyridyl Ru(II) Complexes And Their Electrochemical Properties"
Bull. Korean Chem. Soc. 2006 Volume 27, Issue 1 Pages 99-105
Do Nam Lee, Hee Sang Park, Eun Hwa Kim, Young Moo Jun, Ja-Young Lee, Won-Yong Lee*, Byeong Hyo Kim

Abstract: Polyamine dendrimers functionalized with electrochemiluminescent (ECL) polypyridyl Ru(II) complexes, dend-[CO-(CH2)3- mbpy?Ru(L)2]3(PF6)6 (dend: N(CH2CH2NH)3-, L: bpy, o-phen, phen-Cl, DTDP), were synthesized through the complexation of dendritic polypyridyl ligands to Ru(II) complexes. Their electrochemical redox potentials, photoluminescence (PL), and relative ECL intensities were studied. The ECL emissions produced by the reaction between the electro-oxidized Ru3+ species of polyamine dendrimers and tripropylamine as a coreactant were measured in a static system with potential cycles between 0.8 and 1.3 V or through flow injection analysis with a potential of +1.3 V, and were compared to that of [Ru(o-phen) 3](PF6)2. Dend-[CO-(CH2) 3-mbpy?Ru(bpy)2]3(PF6) 6 showed an ECL intensity that was two-fold greater than that of the reference complex [Ru(o-phen)3](PF6)2.

"The Construction And Use Of A Windowless Optical Cell For The Flow Injection Analysis Of Chloride Ion"
Bull. Korean Chem. Soc. 2005 Volume 26, Issue 1 Pages 36-37
Jae-Ho Lee, Mee-Ae Han, Seong-Woo Kang, Seong-Seok Seo, Hoon Hwang*

Abstract: No abstract

"Determination Of Uric Acid By Chemiluminescence Measurement Using Tris(2,2?-bipyridine)ruthenium(II)-octylphenylpolyglycol Ether System"
Bull. Korean Chem. Soc. 2004 Volume 25, Issue 8 Pages 1177-1181
Young-Sang Kim*, Jeung Hee Park, Yoon-seok Choi

Abstract: The determination of uric acid in urine samples was studied by a chemiluminescence measurement using tris (2,2?-bipyridine)ruthenium(II)- octylphenylpolyglycolether [Ru(bpy)32+-OPE] system. The oxidized uric acid by Ce(IV) excited Ru(bpy)32+ to emit a chemiluminescence in this system so that the intensity was stoichiometrically dependent upon the concentration of uric acid. In a reaction cell, a luminescent reagent, oxidant, surfactant and sulfuric acid were flowed into and mixed with a taken sample. Experimental conditions were optimized to obtain the maximum intensity of chemiluminescence. Each reactant solution of more than the following concentration gave a good result: 2 x 10^-4 M Ru(bpy)32+, 0.01 M Ce(IV), 6% OPE, and 0.33 M H 2SO4. Any interferences were not shown in this process by the investigation of concomitant constitutes such as albumin, creatine, lactic acid, glucose, urea, Cl-, Mg2+, Ca2+ and so on. The linearity of a calibration curve was good with r = 0.998, the relative standard deviation of the slope was 3.3% and the detection limit was 5.6 ng/mL. The recoveries of 80 to 91% were obtained from the standard spiked samples. The values were little bit low, but this procedure could be considered to be reliable for the determination of trace uric acid in urine samples.

"Mechanically Immobilized Copper Hexacyanoferrate Modified Electrode For Electrocatalysis And Amperometric Determination Of Glutathione"
Bull. Korean Chem. Soc. 2001 Volume 22, Issue 8 Pages 816-820
D. Ravi Shankaran, S. Sriman Narayanan

Abstract: A new copper hexacyanoferrate modified electrode was constructed by mechanical immobilization. The modified electrode was characterized by cyclic voltammetric experiments. Electrocatalytic oxidation of glutathione was effective at the modified electrode at a significantly reduced overpotential and at broader pH range. The modified electrode shows a stable and linear response in the concentration range of 9 x 10^-5 to 9.9 x 10^-4 M with a correlation coefficient of 0.9995. The modified electrode exhibits excellent stability, reproducibility and rapid response and can be used in flow injection analysis for the determination of glutathione.
Detector

"Determination Of Cholesterol By A Diode Laser/Fiber Optic Colorimetric Spectrometer"
Bull. Korean Chem. Soc. 2000 Volume 21, Issue 4 Pages 389-392
Sung-Ho Kim,* Sung Man Nam, Gill Sang Byun, Shin Young Yun, and Seongsik Hong

Abstract: A simple and inexpensive colorimetric spectrometer for determining total cholesterol has been developed,comprising a diode laser as the light sourcoptical fibers for the light guide and a photodiode as the detector.The stabilty and performance of the new system was investigated by obtaining the calibration curve for stan-dard cholesterol solutions. The total cholesterol in humanserum was also measured by the analyzer and com-pared with the value obtained by a conventional spectrometer. The results showed that the developed spectrometer was useful for the determination of cholesterol levels. The visible diodelaser used in the study exhibited good spectroscopic and operational properties for colorimetric absorption spectrometry and could be a key component for the development of a simple and economical analyzer.

"Development Of An Ultrasonic Nebulizer Using A Domestic Humidifier"
Bull. Korean Chem. Soc. 1999 Volume 20, Issue 11 Pages 1277-1280
Pyung Heum Yeon, Young Min Cho, and Yong-Nam Pak*

Abstract: An inexpensive ultrasonic nebulizer (USN) was developed utilizing a home humidifier. The ultrasonic transducer was taken from a commercial USN and the power supply was from a humidifier. Sample was continuously fed into the nebulizer and the detection limit was improved 3-20 times over a pneumatic nebulizer. Undesirably, noise in signal was also increased several times. 0.5 ppm of Mn was used as an internal reference and the 'long-term' drift could be successfully corrected. Since the noise contained high and low frequency components, both could be effectively removed only by the real-time correction method such as the Myer-Tracy method, where the reference line was simultaneously monitored with the analytical lines. The performance of USN was tested with NIST SRMs and showed good agreement with the certified values.
Cadmium Beryllium Bismuth Nickel Lead Zinc Tin NIST 1566 NIST 1547 Mass spectrometry Apparatus Nebulizer Optimization

"Application Of A Membrane Desolvator To The Analysis Of Organic Solvents In Inductively Coupled Plasma Atomic Emission Spectrometry"
Bull. Korean Chem. Soc. 1999 Volume 20, Issue 9 Pages 1040-1044
J. S. Lee and H. B. Lim*

Abstract: A µporous PTFE membrane desolvator (MMD) was built and evaluated for the on-line removal of organic solvents to facilitate the determination of trace metal contaminants in the solvents by ICP-AES. Three organic solvents, isopropyl alcohol (IPA), methanol, and dimethy sulfoxide (DMSO) were studied. The MMD reduced organic solvent concentration in the sample aerosol stream by 82% to 89%, as indicated by monitoring C(I) emission. Net signal intensity of Fe, Al, and Cu was increasing with higher organic solvent concentration, with the rate of increase being solvent dependent. The signal intensities for Mg and Pb followed the trend with the C(I) signal. Changing the sweep gas flow rate affected the optimum signal intensity. Wine samples were analyzed by the method of standard addition. The concentrations of B, Al, and Mg were determined with a relative precision of less than 2.3%.

"Copper Oxide-Modified Polymeric Composite Electrodes For Amperometric Detection Of Carbohydrates In LCEC Analysis"
Bull. Korean Chem. Soc. 1997 Volume 18, Issue 9 Pages 952-957
Hyekyoung Chung and Jongman Park*

Abstract: Modified polymeric composite electrodes having highly dispersed CuO particles through the electrode matrix were prepared for LCEC or flow injection analysis of carbohydrates. The composite electrodes were prepared by incorporating carbon black and highly dispersed copper oxide particles in polystyrene matrix cross-linked with divinylbenzene. The analytical characteristics of the electrodes for LCEC and flow injection analysis of carbohydrates were evaluated. Improved performance in LCEC and flow injection analysis of carbohydrates is demonstrated in terms of sensitivity, reproducibility, stability and surface renewability. It was possible to get improved performance of the electrodes as well as adaptability of the electrodes for practical applications by employing highly dispersed catalyst particles through the electrode matrix and robust polymeric electrode matrix.

"Pulsed Amperometric Detection Of Metal-ions Complexing With EDTA In A Flow Injection System"
Bull. Korean Chem. Soc. 1997 Volume 18, Issue 3 Pages 316-318
Joon-Woo Lee, In-Hyeong Yeo, and Chong Hong Pyun

Abstract: A general and universal detection method, which can be used in high performance liquid chromatography (HPLC) and flow injection analysis (FIA) system for the determination of any metal ions complexing with ethylenediaminetetraacetic acid (EDTA), is demonstrated. Pulsed amperometric detection scheme is applied in a now-through thin layer electrochemical cell at an Au working electrode. Fluctuation of peak current level at the same flow rate of carrier solution is minimized at this solid working electrode, whereas not at a dropping mercury electrode. Removal of dissolved oxygen can be omitted with this detection method, which is a required step for cathodic detection methods. Also, a group of metal ions can be determined selectively and indirectly with this detection scheme. 9 References
Metals, rare earth Amperometry Electrode EDTA Complexation

"Optimization Of Wave Forms For Pulsed Amperametric Detection Of Cyanide And Sulfide With Silver-Working Electrode"
Bull. Korean Chem. Soc. 1996 Volume 17, Issue 2 Pages 143-147
Sung-Woo Park, Sung-Wook Hong, and Jae-Hoon You

Abstract: A continuous potential pulse is applied to a silver-working electrode on a pulsed amperometric detector (PAD) for detection of free cyanide and sulfide. The moving phase is 0.1 M sodium hydroxide, 0.5 M sodium acetate and 5% (v/v) ethylenediamine mixture, and the flow rate is 0.7 mL/min. Optimized pulse conditions include a -200 mV (vs. Ag/AgCl reference electrode) detection potential(Ed) for 60 msec and 50 mV cleaning potential (Ec) for 120 msec. The silver working electrode surface is not poisoned by cyanide or sulfide, and the PAD maintains long-term stability without loss of sensitivity and reproducibility at these pulse conditions. The detection limit of cyanide and sulfide separated by ion chromatography using an anion exchange column is 0.1 ppm and 0.05 ppm, respectively.

"Minimization Of Asymmetry Potential In ETH 129-Based Calcium-Selective Membrane Electrodes"
Bull. Korean Chem. Soc. 1995 Volume 16, Issue 11 Pages 1033-1037
Sung Bae Park*, Sarah Chung, Geun Sig Chat, and Hal Dong Kim

Abstract: PVC-based calcium-selective electrodes doped with ETH 129 usually suffer from a shift in the standard potential when they are in contact with protein-containing solutions (e.g. blood serum) after being calibrated with aqueous standards. The shift is due to the development of asymmetry potential in inherently symmetric PVC membranes through the contamination of outer membrane surface by proteins in the biological samples. Membranes prepared with polyurethane showed much reduced shifts in terms of standard potential. This study was performed with a flow-injection system following a protocol designed to observe minor shifts in baseline potential. Other electrochemical properties of the system, including selectivity and response slope, were similar to those obtained with regular PVC-based ones. PVC-based calcium selective membrane electrodes, doped with commonly used ETH 1001, were also tested to compare their electrochemical performances.

"Determination Of Nitrate In Chromium Plating Solution With Nitrate-Selective Electrodes"
Bull. Korean Chem. Soc. 1995 Volume 16, Issue 3 Pages 221-226
You Ra Kang, Won Leet, Hwang Huh*. Geun Sig Cha, and Hakhyun Nam*

Abstract: A method for determining nitrate in post treatment chromium plating solutions with PVC-based nitrate-selective electrodes is described. PVC-based nitrate-selective membranes which contain TDMANO3 ion-exchanger in PVC/NPOE, PVC/DOA or PVC/DBP matrices, and a commercially available Corning electrode (No. 476134) have been compared in respect of their detection limits, response slopes, selectivities at various pHs, and dynamic response to the hydrochromate ion in basic condition. The PVC/DBP/TDMANO3 membrane electrode was chosen as the ISE detector for the determination of nitrate in the presence of hydrochromate interference. The amount of nitrate in real post treatment chromium plating solution could be determined successfully with this electrode in both static and flow-injection measurements when the sample was properly diluted with an alkaline buffer.

"Flow Injective Determination Of Thiourea By Amperometry"
Bull. Korean Chem. Soc. 1994 Volume 15, Issue 12 Pages 1038-1042
Joon-Woo Lee, Sun-Il Mho, Chong-Hong Pyun, and In-Hyeong Yeo*

Abstract: The amperometric responses of thiourea were studied in 0.1 M NaOH by flow injection analysis. DC amperometric and pulsed amperometric detection methods were applied for the determination of thiourea at novel metal electrodes such as Pt and Au. Triple-step potential waveforms were adopted in the pulsed amperometric detection. With an optimized pulsed waveform, the current for the oxidation of thiourea was examined with the variation of flow rate of carrier solution and with the change in the amount of sample injected. Gold working electrode turned out to be better in sensitivity and signal to noise ratio than Pt electrode in the pulsed amperometric detection of thiourea. Detection limit is estimated to be 5.33 x 10^-5 M with this detection method.

"Development Of Continuous Flow Microwave Digestion Procedures For Analysis Of Trace Metal Oxides In Water Using Ion Chromatography"
Bull. Korean Chem. Soc. 1994 Volume 15, Issue 9 Pages 786-791
Youn Doo Kim*, Gae Ho Lee, Hyung Seung Kim, Dong Soo Kim, and Kwang Kyu Park*

Abstract: A simple and rapid sample pretreatment process necessary for determination of metal oxides in water was proposed. Samples were injected into the continuous-flow tube installed inside the microwave oven and the treated samples were cooled before entered to the Ion Chromatography (IC) or Inductively Coupled Plasma (ICP). By coupling this microwave digestion system with IC or ICP, a fully automatic analytical procedures may be easily established. In this study, two different types of digestion methods were considered; the open tubing method (OTM) and the restraint tubing method (RTM). The RTM was proved to be 3 times faster in digestion period and 10 times higher in detection range than the OTM. Validation of proposed sample digestion system was carried out by using an ICP. The results showed that both of continuous-flow methods, the OTM and the RTM were comparable in accuracies with the conventional batch-type vessel digestion method.

"Studies On The Spectrophotometric Determination And Electrochemical-behavior Of Heavy Lanthanide Ions In Nonaqueous System And Heavy-metal Chelate Complexes With Bidentate Ligands. 1. Flow Injection Spectrophotometric Determination Of Heavy Lanthanide Io"
Bull. Korean Chem. Soc. 1993 Volume 14, Issue 1 Pages 59-62
Sam-Woo Kang, Chong-Min Park, Kwang-Hee Cho and Hong-Seock Han

Abstract: Spectrophotometric determination of some heavy lanthanide ions by flow injection method is described. Xylenol Orange forms water soluble chelates with lanthanide ions in a tris[hydroxymethyl]-aminomethane-buffered medium having pH 8.3 and containing cetyltrimethylammonium bromide. The molar absorptivities of Ln(III)-XO complexes were increased by the ternary system with cetyltrimethylammonium bromide with the concomitant bathochromic shift of absorption maxium compared to those of the binary system without cetyltrimethylammonium bromide. The calibration curves are linear in the range 0.25-1.00 ppm for Gd(III), Dy(III), Er(III), Tm(III) and Yb(III) and the dynamic range are very wide. The detection limits (S/N=2) are from 2 ppb for Gd(III) to 30 ppb for Yb(III) and the relative standard deviations are from 1.2% for 0.5 ppm Gd(III) to 1.8% for 0.5 ppm Yb(III). The sample throughput was ~50 h-1.
Lanthanides Spectrophotometry Chelation

"Semi-automatic Hydride Generation And Atomic Absorption Determination Of Bismuth With Insitu Concentration In A Graphite Furnace"
Bull. Korean Chem. Soc. 1991 Volume 12, Issue 3 Pages 290-295
Yong-Keun Lee*, Dong Soo Lee, Byung Mok Yoon, and Hoon Hwang

Abstract: A semi-automatic method for the determination of dissolved bismuth at parts per trillion levels is described. The method involves bismuthine generation, in situ collection of bismuthine in a graphite furnace, and atomic absorption detection. In order to facilitate semi-automation of bismuthine generation and separation from aqueous solution, Gore-tex microporous PTEE membrane is used. The absolute detection limit, taken as three times the standard deviation of the instrument noise is 2 pg. The precisions are 3.1% for 100 pg and 1.9% for 1 ng of bismuth, respectively. As many as 90 measurements can be made in an hour.
Bismuth Environmental Marine Environmental Spectrophotometry Interferences Volatile generation Volatile generation

"Indirect Determination Of Rare-earth Metals By Flow Injection Analysis With Amperometric Detection"
Bull. Korean Chem. Soc. 1991 Volume 12, Issue 1 Pages 10-12
In-Hyeong Yeo*, Ke-Chon Choi, and Tae Yoon Eom

Abstract: A flow cell is illustrated for carrying out differential-pulse polarography in conjunction with flow injection analysis. A three-electrode system was used, with a dropping Hg working electrode and a Pt-wire counter electrode vs. SCE. Sample solution were injected into a stream of 1 M ammonium acetate buffer solution of pH 4.8 (supporting electrolyte) and this stream was mixed with the same supporting electrolyte, containing 0.5 mM diethylenetriaminepenta-acetic acid (I). The concentration. of I unconsumed in complexing the rare-earth metals was determined by oxidation at 100 mV vs. SCE. The decrease in current was proportional to concentration. in the range 1 to 7 x 10^-5 for Tm(III), Ho(III) and Yb(III). The detection limit (0.5 µg injected) was not as good as by spectrophotometric methods, but may be improved by better cell design.
Metals, rare earth Amperometry Electrode Electrode Polarography Buffer Complexation Indirect