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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Xi Chen

Abbrev:
Chen, X.
Other Names:
Address:
Department of Chemistry, Xiamen University, Xiamen 361005, China
Phone:
+34-968-367-400
Fax:
+34-968-364-148

Citations 7

"Study And Application Of Tris(2,2'-bipyridine)ruthenium Electrochemiluminescence In Flow Injection Analysis And High Performance Liquid Chromatography"
Sepu 1998 Volume 16, Issue 4 Pages 301-305
Chen Xi

Abstract: A review with 36 references. This review covers fundamental development of tri (2,2'-bipyridine) ruthenium (II)-electrochemiluminescence during the last 30 yr. Its applications in flow injection analysis and HPLC also are discussed.
Chemiluminescence Review

"Study Of The Electrochemiluminescence Based On Tris(2,2'-bipyridine) Ruthenium(II) And Alcohols In A Flow Injection System"
Microchem. J. 1998 Volume 58, Issue 1 Pages 13-20
Xi Chen, Masanori Sato and Yongjing Lin

Abstract: The luminescence electrooxidation of monohydric alcohols and polyhydric alcohols in tris(2,2'-bipyridine) ruthenium(II) [Ru(bpy)2+3] alkaline solutions on a glassy carbon electrode has been studied. At a potential of +1.30 V (vs Ag/AgCl), Ru(bpy)2+3 was oxidized to Ru(bpy)3+3. The luminescence wavelength of 608 nm could be found because Ru(bpy)3+3 reacted on alkoxide radical to produce the excited state. Study of the luminescence intensities of monohydric alcohols showed that luminescence intensity decreased as alkyl chain length of the molecules increased. With the increase in the number of hydroxyl groups in a molecule, luminescence intensity increased for polyhydric alcohols.
Alcohols, polyhydric Chemiluminescence Electrode

"Preliminary Electrochemiluminescence Study Of Allantoin In The Presence Of Tris(2,2-bipyridine) Ruthenium (II)"
Luminescence 2005 Volume 20, Issue 3 Pages 109-116
Xi Chen, Ying Tao, Li Zhao, Zenghong Xie, Guonan Chen

Abstract: Electrochemiluminescence (ECL) based on allantoin and tris(2,2?- bipyridine)ruthenium (II) [Ru(bpy)32+] was studied in aqueous alkaline buffer solution (pH 11.0). In a flowing system, the eluted allantoin was mixed with 1.0 mmol/L Ru(bpy)32+. When the solution passed through a thin layer flow electrolytic cell equipped with a glassy carbon disc electrode (22.1 mm2), both hydroxyl groups of allantoin and Ru(bpy)32+ were oxidized at the potential of +1.50 V (vs. Ag/AgCl). The luminescence with ?max 610 nm caused by the reaction of electrolytically formed Ru(bpy)32+ with alkoxide radical to generate the excited state of Ru(bpy)32+*, A possible ECL process of allantoin in Ru(bpy)32+ alkaline solution has been discussed. In addition, the factors affecting the ECL response of allantoin are also investigated.

"Determination Of Aniline And Benzidine By Using Electrochemiluminescent Quenching Of Ru(bpy)32+-C2O42- System"
Fenxi Huaxue 2004 Volume 32, Issue 11 Pages 1478-1480
Yi ?.?., Li ?.?., Tao Ying, Chen Xi

Abstract: Aniline and benzidine were found to quench strongly the electrochemiluminescence (ECL) of the Ru(bpy)32+-C 2O42- system when a working glassy carbon electrode was maintained at 1.50 V (vs. Ag/AgCl) in pH 6.2 phosphate buffer. A flow injection procedure with electrochemiluminescent quenching detection has been developed for determination of aniline and benzidine. The method exhibits a good reproducibility and stability with a detection limit of 5.0 x 10^-7 mol/L for aniline and 2.0 x 10^-7 mol/L for benzidine, respectively. The relative standard deviations (n = 6) were 3% and 2.5% for determination of 1.0 x 10^-5 mol/L aniline and benzidine, respectively. The mechanism of the inhibition effects was proposed in the preliminary way.

"Study Of The Electrochemiluminescence Based On Tris (2,2?-bipyridyl) Ruthenium (II) And Some Nervous Amine Compounds Using Flow Injection Analysis"
Fenxi Huaxue 2002 Volume 30, Issue 5 Pages 513-517
Chen Xi, Li ?.?., Li Zhen, ? ?.?., Wang Xiaoru, Wang Bo

Abstract: A new electrochemiluminescence (ECL) method for the detection of methamphetamine (METH) and some nervous amine compounds is described. The pH of mobile phase and applied potential on glassy carbon electrode obviously influence the intensity of the ECL of METH. The mobile phase was selected as 0.1 mmpl/L Ru (bpy)3Cl2 in 0.05 mol/L NaH2 PO4-NaOH (pH 9.0) buffer. The studies of the effect of applied potential and flow rate on ECL showed that METH gives the brightest light emission at the potential of + 1.55 V and at the flow rate of 0.4 mL/min. A linear relationship was obtained from 6.84 x 10^-11 - 6.84 x 10^-3 mol/L with a correlation coefficient of R2 = 0.9906 and the detection limit was 2 x 10^-1 mol/L under the experimental condition. The effect of surfactants on ECL was studied. The work also included the study of ECL of related compounds such as codeine, cocaine, morphine and so on. Cyclic voltammetry showed that their different oxidation currents might lead to their different ECL intensity. The method was simple, economical, sensitive, useful and provided some evidences for scout cases.

"Electrochemiluminescent Behaviour Of Vitamin B-1 (thiamine) And Tris(2,2 -bipyridyl) Ruthenium In A Flow System"
Acta Chim. Sin. 2000 Volume 58, Issue 5 Pages 563-566
CHEN Xi*,CHEN Wei,WANG Xiao-Ru

Abstract: Upon the electrochemical oxidation of tris(2,2 - bipyridyl) ruthenium(II) [Ru(bpy)(3)(2+)] and vitamin Bl(thiamine) in 0.1 mol/L NaOH (aqueous solution), a bright electrochemiluminescence (ECL) was observed. Vitamin B1 was transformed into a yellow pseudo - base and a colorless thiol formed when treated with 0.1 mol/L NaOH for 5 and 20 min, respectively. The thiol form was oxidized at + 0.88 V (vs.Ag/AgCl) to produce a free radical, which reacted with Ru(bpy)(3)(3+) at a glassy carbon electrode. The light emission at wavelength 609 nm was caused by the transition of the excited state of Ru(bpy)(3)(2+) to its ground state. The pH of solution effected the hydrolysis of vitamin B1, which caused the different light emission intensity of Ru(bpy)(3)(2+) and vitamin B1 solution. ECLs of some coexisting substances such as amino acids, sugars, hydroxyl carboxylic acids, vitamin Bz, Bg were also detected in this now system.
Vitamin B1 Tris(bipyridine)ruthenium(II) chloride Chemiluminescence

"Determination Of Sophoridine And Related Lupin Alkaloids Using Tris(2,2-bipyridine)ruthenium Electrogenerated Chemiluminescence"
Anal. Chim. Acta 2002 Volume 466, Issue 1 Pages 79-86
Xi Chen, Changqing Yi, Meijin Li, Xin Lu, Zhen Li, Peiwei Li and Xiaoru Wang

Abstract: Electrogenerated chemiluminescences (ECLs) based on tris(2,2-bipyridine)ruthenium(II) (Ru(bpy)32+) and lupin alkaloids, for instance, sophoridine (SRI), matrine (MT), sophoranol (SR) and sophocarpine (SC) in an aqueous alkaline buffer solution (pH 9.0) are studied. The light emission is mainly caused by an electro-oxidation reaction between tertiary amino group on the alkaloid compounds and Ru(bpy)32+ in a thin layer flow cell equipped with a glassy carbon disc electrode (22.1 mm2) at the potential of +1.50 V (versus Ag/AgCl). The luminescence wavelength of 610 nm confirmed that ECL is caused by Ru(bpy)32+* to its ground state. ECL intensities of these lupin alkaloids are affected by the substituent character, three-dimensional conformation of hydrogen on β-carbon atom. Ionization potentials taken from calculation data further confirm the experimental results. In addition, the factors affecting the determination and HPLC separation of the four alkaloids are also investigated.