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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Guo Nan Chen

Abbrev:
Chen, G.N.
Other Names:
Guonan Chen, Guo-nan Chen
Address:
Department of Chemistry, Fuzhou University, Fuzhou, Fujian 350002, China
Phone:
+86-591-7893315
Fax:
+86-591-3713866

Citations 14

"Electrochemiluminescent Behavior Of Allopurinol In The Presence Of Ru(bpy)32+"
Talanta 2006 Volume 68, Issue 5 Pages 1544-1549
Yuwu Chi, Junlin Xie and Guonan Chen

Abstract: The electrochemiluminescent (ECL) response of allopurinol was studied in aqueous media over a wide pH range (pH 2-13) using flow injection (FI) analysis. It was revealed that allopurinol itself had no ECL activity, but could greatly enhance the ECL of Ru(bpy)32+ in alkaline media giving rise to a sensitive FI-ECL response. The effects of experimental conditions including the mode of applied voltage signal, the potential of working electrode, pH value, the flow rate of carrier solution, and the concentration of Ru(bpy)32+ and allopurinol on the ECL intensity were investigated in detail. The most sensitive FI-ECL response of allopurinol was found at pH 12.0, where the FIA-ECL intensity showed a linear relationship with concentration of allopurinol in the range 1 x 10^-8 mol L-1 to 5 x 10^-7 mol L-1, and the detection limit was 5 x 10^-9 mol L-1.

"Flow Injection Analysis Of Trace Amounts Of NADH With Inhibited Chemiluminescent Detection"
Talanta 2002 Volume 57, Issue 5 Pages 961-967
Nianbing Li and Guonan Chen

Abstract: The flow injection analysis of NADH was developed based on its inhibitory effect on a luminol-potassium hexacyanoferrate(III) chemiluminescence (CL) system. Under the optimum conditions, the decreased CL intensity was linear to the NADH concentration in the range of 5.0 x 10^-8-2.0 x 10^-5 mol L-1. The relative standard deviation was 1.24% for eight determinations of 1.0 x 10^-6 mol l-(1) NADH and the detection limit (3s(b1)/S) was 2.0 x 10^-8 cool L-1. The study of interfering substances was also performed and the method was applied to the direct determination of trace amounts of NADH in synthetic samples with satisfactory results. Moreover, the inhibitory mechanism of CL was investigated with CL spectra, fluorescence spectra and UV-visible absorption spectra. (C) 2002 Published by Elsevier Science B.V.

"Coulometric Detector Based On Porous Carbon Felt Working Electrode For Flow Injection Analysis"
Talanta 2000 Volume 53, Issue 3 Pages 651-660
Guo Nan Chen, Jiang Sheng Liu, Jian Ping Duan and Hong Qing Chen

Abstract: A coulometric detector based on carbon felt as working electrode has been designed. Ascorbic acid, hydroquinone, gallic acid and sulfur dioxide were used as electroactive compounds to determine the electrochemical characteristics of this detector. Phe coulometric conversion efficiency, selectivity, linear response range, detection limit and mass transfer coefficient were investigated in order to use the detector as a cleanup device in a flow injection system with dual-detector. This system has been used for determination of sulfur dioxide in wine, and the results are compared to those from the aspiration-oxidation method.

"Flow Injection Chemiluminescent Detection Of Trace Co(II) With Dibromoalizarin Violet-H2O2-CTMAB System"
Microchim. Acta 1994 Volume 116, Issue 4 Pages 227-238
Guo-Nan Chen , Jian-Ping Duan and Qing-Fu Hu

Abstract: Chemiluminescence was observed when dibromoalizarin violet was oxidized with hydrogen peroxide in alkaline solution. Trace amounts of Co (II) catalyzed this CL reaction strongly, especially in the presence of the cationic surfactant cetyltrimethylammonium bromide, and the CL intensity was proportional to the concentration of Co(II). A flow injection system with CL detection was established to investigate this CL system. The optimum conditions for this CL reaction were investigated in detail, and the optimized flow injection parameters were determined by the modified simplex method. A CL analytical method for determination of ultratrace amounts of Co (II) was developed with a detection limit of 4 pg/mL. It was used for analysis of natural water samples, and the results compare very well with those from GFAAS. A possible mechanism for this CL reaction is proposed on the basis of studying CL spectra, absorption spectra, fluorescent spectra and HMO treatment for the reagent molecule. The effects of various types of surfactants on CL reaction are also discussed.

"Determination Of Methyltestosterone Using Flow Injection With Chemiluminescence Detection"
Luminescence 2005 Volume 20, Issue 3 Pages 231-235
Zenghong Xie, Xiaoqing Ouyang, Liangqia Guo, Xucong Lin, Guonan Chen *

Abstract: Methyltestosterone (MT) enhanced the chemiluminescence of potassium permanganate-sodium thiosulphate system in sulphuric acid medium, and this was used as the basis of a novel flow-injection chemiluminescence method for the determination of methyltesterone. Under optimum conditions, the linear response of MT was in the range 3.0 x 10^-8 - 8.0 x 10^-6 g/mL, and the detection limit for determination of MT was 1.0 x 10^-8 g/mL. The method was applied to the analysis of fish with recovery in the range 88.0-113.8% with an average RSD of 1.66% (n = 8).

"Determination Of Carbofuran By Flow-injection With Chemiluminescent Detection"
Luminescence 2005 Volume 20, Issue 3 Pages 226-230
Zenghong Xie, Xiaoqing Ouyang, Liangqia Guo, Xucong Lin, Guonan Chen *

Abstract: It was found that carbofuran enhances the chemiluminescence reaction between sodium sulphite and Ce4+ in sulphuric acid, and this formed the basis of a flow-injection system with chemiluminescence detection for determination of carbofuran. Under optimum conditions, the enhanced chemiluminescence intensity was linear, with the concentration of carbofuran in the range 8 x 10^-8-1.0 x 10^-5 g/mL, with a detection limit of 2.84 x 10^-8 g/mL (3s). The proposed method was applied to the analysis of carbofuran in cabbage, with satisfactory results.

"A Study On The Micelle-sensitized Ce(IV)-Na2S2O3-norfloxacin Chemiluminescence System And Its Applications"
Luminescence 2005 Volume 20, Issue 3 Pages 220-225
Zenghong Xie, Sulan Liao, Guonan Chen*

Abstract: A new chemiluminescence (CL) flow-injection method was developed for the determination of norfloxacin. The method is based on the CL reaction of norfloxacin with sodium thiosulphate and Ce(IV) in sulphuric acid medium sensitized by sodium dodecylsulphate. Under optimum conditions, the CL intensity is proportional to the concentration of the norfloxacin in the range 3.89 x 10^-8-7.18 x 10^-6 g/mL. The detection limit (3 s[sol ]k) was 2.21 x 10^-9 g[sol ]mL for norfloxacin. The method has been applied successfully to the determination of norfloxacin in pharmaceutical formulations and human urine. The mechanism for this chemiluminescence system is discussed.
Norfloxacin Pharmaceutical Urine Chemiluminescence Optimization Micelle

"Determination Of Oxytetracycline By Flow Injection With Chemiluminescence Detection"
Luminescence 2005 Volume 20, Issue 3 Pages 129-134
Liangqia Guo, Zenghong Xie, Xintong Bian, Xucong Lin, Weilin Zhang, Xiaohua Liu, and Guonan Chen*

Abstract: A flow-injection chemiluminescent method for the determination of oxytetracycline was developed. The method is based on an enhancement by oxytetracycline of the chemiluminescence light emission of tris(2,2-bipyridine) ruthenium (II), generated by the continuous oxidation of tris(2,2-bipyridine) ruthenium (II) by cerium (IV) sulphate in sulphuric acid. Under the optimum conditions, the calibration curve was linear over the range 1.0 x 10^-7-1.0 x 10^-5 g[sol ]mL for oxytetracycline with the linear equation: INT = 148.77 x C + 0.6637 (R2 = 0.9994). The detection limit was 4.52 x 10^-8 g[sol ]mL. The proposed method was also successfully used to determine oxytetracycline in pharmaceutical formulations. The mean recovery of determination of oxytetracycline was 92.73%. A mechanism for the chemiluminescence enhancement by oxytetracycline of tris(2,2-bipyridine)-ruthenium (II) and cerium (IV) sulphate system is also proposed.

"Flow Injection Chemiluminescent Determination Of Tetracycline Using A Tris(2,2-bipyridine)ruthenium(II)-cerium(IV) Sulphate System"
Luminescence 2004 Volume 19, Issue 2 Pages 64-68
Liangqia Guo, Zenghong Xie, Xucong Lin, Xiaohua Liu, Weilin Zhang, Guonan Chen *

Abstract: A flow injection chemiluminescence method for the determination of tetracycline was developed. The method is based on an enhancement by tetracycline of the chemiluminescence light emission of tris(2,2-bipyridine)ruthenium(II). In sulphuric acid medium, the chemiluminescence is generated by the continuous oxidation of tris(2,2-bipyridine)ruthenium(II) by cerium (IV) sulphate. The light-emission intensity is greatly enhanced in the presence of tetracycline. Under the optimum conditions, the calibration curve is linear over the range 3.75 x 10^-8 - 1.5 x 10^-5 g/mL for tetracycline with the linear equation: INT = 205.898 x C - 20.442 (R2 = 0.9974). The detection limit is 3.27 x 10^-8 g/mL. The proposed method was also successfully used to determine tetracycline in pharmaceutical formulation (mean recovery of tetracycline, 100.7%).

"Determination Of Procaine Hydrochloride Using Flow Injection Inhibitory Chemiluminescence"
Luminescence 2003 Volume 18, Issue 3 Pages 125-130
Nianbing Li, Yuwu Chi, Jian Wang, Jianping Duan, Guonan Chen

Abstract: A new flow injection chemiluminescent method has been developed for the determination of procaine hydrochloride, based on the inhibition of the chemiluminescence reaction of luminol-hydrogen peroxide by procaine hydrochloride. The influence of several surfactants and -cyclodextrin on the chemiluminescence intensity were studied. It was found that -cyclodextrin enhanced the decrease in chemiluminescence intensity. The method is simple, convenient and sensitive, with a detection limit (3 ) of 0.08 µg/mL. The decreased chemiluminescence intensity is linear, with the concentration of procaine hydrochloride in the range 0.2-100.0 µg/mL and 100.0-400.0 µg/mL. The relative standard deviation for 10 repeated measurements were 4.5% and 3.4% for 1.0 and 20.0 µg/mL procaine hydrochloride, respectively. The method has been successfully applied to the determination of procaine hydrochloride in injection solutions of this drug.

"Study On A Coulometric Detector Based On A Porous Carbon Felt As A Working Electrode For Flow Injection Analysis And Its Application"
Fenxi Huaxue 1995 Volume 23, Issue 3 Pages 292-296
Chen, G.N.

Abstract: Construction of the cited detector and its incorporation into a flow injection analyzer. is described. Ascorbic acid, hydroquinone, gallic acid and SO2 were used as model analytes; the detection limits were 20, 10 and 30 nM, and 8 µM, respectively. Other properties were also investigated (e.g., linear range, selectivity). The detector was used to replace the 'clean-up' cell in the dual-detector flow injection analysis system for the determination of SO2 in wine; optimum conditions were 1 mM H2SO4 as carrier (0.4 ml/min) and a detector working potential at 0.41 V vs. an ion-couple electrode. The results were compared with those obtained by the aspiration-oxidation method.
Ascorbic acid Gallic acid Hydroquinone Sulfur dioxide Wine Coulometry Electrode Method comparison

"A Study On The Electrochemical And Electrochemiluminescent Behavior Of Homogentisic Acid At Carbon Electrodes"
Electroanalysis 2003 Volume 15, Issue 3 Pages 208-218
Yuwu Chi, Jianping Duan, Zheng Feng Zhao, Hongqinq Chen, Guonan Chen

Abstract: The electrochemical oxidation and electrochemiluminescent behavior of homogentisic acid (HGA) has been studied in aqueous solutions over a wide pH range by linear sweep voltammetry, cyclic voltammetry, chronocoulometry at a glassy carbon electrode, by controlled potential electrolysis at a large area spectroscopic graphite electrode, and by spectroelectrochemistry at an optically transparent drilled holes graphite (DHG) electrode in a thin-layer cell. The studies reveal that the electrochemical oxidation of HGA at carbon electrodes is a reversible process involving two-electron, two-proton transfer. In addition to the electrochemical oxidation, the chemical oxidation of HGA by dissolved oxygen was investigated by spectroscopic method combined with voltammetry. It was revealed that HGA is fairly stable in strongly acidic media but readily oxidized by dissolved oxygen in alkaline media giving rise to 1,4-benzoquinone-2-acetic acid, the same product as that of electrooxidation of HGA. This oxidation product is stable in acidic, neutral and weakly alkaline media, but can further degrade in strongly alkaline media yielding oxalate as the final product. The electrochemiluminescent mechanism of HGA in the presence of Ru(bpy)32+ at a glassy carbon electrode was also investigated in detail, based on which a sensitive ECL method for determination of HGA was developed, and the detection limit was 3.0 x 10^-8 mol L-1.
Homogentisic acid Chemiluminescence Electrode Optimization

"Flow Injection Analysis System Equipped With A Newly Designed Electrochemiluminescent Detector And Its Application For Detection Of 2-thiouracil"
Anal. Chem. 2006 Volume 78, Issue 5 Pages 1568-1573
A. Caballo-López and M. D. Luque de Castro

Abstract: A new flow injection analysis (FIA) system equipped with an electrochemiluminescent (ECL) detector has been developed and applied for the ECL detection of 2-thiouracil. The FIA-ECL system used a specially designed flow-through ECL thin-layer cell to reduce the dead volume, the IR drop across the cell, and the probability of accumulation of gas bubbles in the cell. It was thus envisioned to improve the detection limit of the FIA-ECL method. After being established, the new FIA-ECL system was used to investigate the ECL response of 2-thiouracil in the presence of the ECL of Ru(bpy)32+. It was found that 2-thiouracil could enhance the ECL of Ru(bpy)32+ over a wide pH range (pH 4.0-12.0). A highly sensitive method for detection of 2-thiouracil in biological samples was developed by the new FIA-ECL system after optimizing several experimental conditions, such as the applied potential of the working electrode, the pH value of the aqueous solution, the flow rate of carrier solution, and the concentration of Ru(bpy)32+. © 2006 American Chemical Society.

"Chemiluminescence Determination Of Melatonin And Some Of Its Derivatives Using Potassium Permanganate And Formaldehyde System"
Anal. Bioanal. Chem. 2003 Volume 376, Issue 6 Pages 873-878
Guo Nan Chen, Fu Xin Huang, Xiao Ping Wu, Zheng Feng Zhao and Jian Ping Duan

Abstract: It was found that melatonin and its derivatives, such as N-acetyl- 5-methoxytryptamine (MT), N-acetyl-5-hydroxytryptamine (NAS), 5-Methoxytrypt- amine (5-MT), 5-Methoxyindolyl acetic acid (5-MIAA) and N-acetyl-5-methoxy- 6-hydroxytryptamine (6-HMT) would give chemiluminescence in the acidic potassium permanganate solution, and formaldehyde would enhance this chemiluminescent reaction greatly. The optimum conditions for this chemiluminescent reaction were studied in detail by a flow injection system. A new simple rapid method has been developed under the optimum conditions for determination of melatonin. This method has the advantages of high sensitivity, wide range of linear response and low detection limit. On the basis of investigation of chemiluminescent, fluorescent and UV spectra of melatonin in acidic solution containing potassium permanganate and formaldehyde, a possible mechanism of this reaction was proposed.