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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Huichun Zhao

Abbrev:
Zhao, H.C.
Other Names:
Address:
Department of Chemistry, Beijing Normal University, Beijing 100875, PR Chinab Department of Chemistry, Capital Normal University, Beijing 100037, PR China
Phone:
+86-10-6220-7843
Fax:
+86-10-6220-2075

Citations 12

"Determination Of Rufloxacin Hydrochloride By Terbium Sensitized Chemiluminescence"
Yaoxue Xuebao 2002 Volume 37, Issue 11 Pages 876-879
Y Lu, HC Zhao, CY Sun, L Yi

Abstract: AIM: To study the chemiluminescence mechanism of Tb(III)-RFX-Ce(IV)-Na2SO3 system and establish a new method for the determination of rufloxacin (RFX) in capsules and human urine samples. METHODS: RFX was injected into Na2SO3 standard solution,then mixed with Tb3+, Ce4+ in turn, the chemiluminescence signal was detected by weak luminescence analyzer. RESULTS: The chemiluminescence intensity was linearly related to the concentration of RFX in the range of 2.0 x 10^-9 ? 1.0 x 10^-6 mol L-1 with a detection limit of 3.8 x 10^-10 mol L-1. The familiar excipients such as starch and dextrine do not cause interference. So, this method can be applied to the determination of RFX in tablet. The content and recovery of RFX in urine can be directly detected without pretreatment. CONCLUSION: It provides a simple, rapid, highly sensitive and highly selective method of rufloxacin for pharmacokinetic studies and clinical treatments.

"Flow-injection Analysis Of Two Fluoquinolones By The Sensitizing Effect Of Terbium(III) On Chemiluminescence Of The Potassium Permanganate–sodium Sulfite System"
Talanta 2003 Volume 61, Issue 3 Pages 403-409
Lin Yi, Huichun Zhao, Shilv Chen, Linpei Jin, Dongdong Zheng and Zhenglong Wu

Abstract: A simple, rapid and sensitive method for the determination of two fluoquinolones (FQs), enoxacin (ENX) and ofloxacin (OFLX) is described by using flow injection analysis with potassium permanganate-sodium sulfite chemiluminescence detection. The calibration graphs for ENX and OFLX are linear in the range of 8.0 x 10^-10-1.0 x 10^-5 and 1.0 x 10^-9-1.0 x 10^-6 mol l-1, respectively. The 3s limits of detection are 2.4 x 10^-10 mol L-1 for ENX and 5.6 x 10^-10 mol L-1 for OFLX. The method is applied satisfactorily to the determination of the two FQs in dosage form and urine sample. The possible mechanism is also proposed.

"Flow-injection Chemiluminescence Study Of Ce(IV)–Na2SO3–Tb(III)–fluoquinolone Antibiotic System With DNA"
Spectrochim. Acta A 2003 Volume 59, Issue 11 Pages 2541-2546
Lin Yi, Huichun Zhao, Chunyan Sun, Shilv Chen and Linpei Jin

Abstract: A novel flow injection chemiluminescence (CL) system is developed to determine DNA. According to the fact that DNA linearly quenches the CL intensity of Ce(IV)-Na2SO3-Tb(III)-fluoquinolone antibiotic (FLUQ) system, DNA concentration is determined. The calibration graphs are linear in the range of 0.04-10 µg/ml (for both natural and denatured DNA), and the 3s limits of detection are 7.8 ng/ml (natural DNA) and 9.5 ng/ml (denatured DNA). According to fluorescence spectrum and CL spectrum, and through studying the reaction of Ce(IV)-Na2SO3-Tb(III)-FLUQ with nucleotides and bases, we conclude that DNA counteracts the energy transfer from FLUQ to Tb(III), and this function is related to both bases and phosphate groups in DNA.

"Flow Injection Determination Of Lomefloxacin Based On Photochemically Sensitized Chemiluminescence"
Microchim. Acta 2004 Volume 148, Issue 1-2 Pages 65-70
Chunyan Sun, Ning Lian, Huichun Zhao, Lin Yi and Linpei Jin

Abstract: A photochemical chemiluminescence (CL) method for the determination of lomefloxacin (LFX) is proposed. LFX undergoes a photochemical reaction when irradiated with ultraviolet light, and a complex is formed when the photoproduct reacts with terbium(III), which can greatly enhance the CL of the Ce 4+-Na2SO3 system. Under optimum experimental conditions, the linear range is between 9.0? x x 10^-10 and 1.0? x x 10^-5?M, and the detection limit is 2.2? x x 10^-10^-M. The relative standard deviation for the determination of 5.0? x x 10^-8?M LFX was 3.0% (n?=?11). The method has been successfully applied to the determination of LFX in dosage form, serum samples and urine samples. The recoveries were 97.9-102.3% for serum and urine samples. The possible mechanism is presented. © Springer-Verlag 2004.

"A Study On Terbium Sensitized Chemiluminescence Of Ciprofloxacin And Its Application"
Microchem. J. 2003 Volume 74, Issue 3 Pages 223-230
Ning Lian, Huichun Zhao, Chunyan Sun, Shilu Chen, Yan Lu and Linpei Jin

Abstract: A novel rapid flow injection method with chemiluminescence (CL) detection was established for the determination of ciprofloxacin (CPLX), which is an antibiotic commonly used. The method is based on CL of Ce(IV)-SO32- sensitized by Tb3+-CPLX, and showed the intensive bands characteristic of Tb3+ (5D4->7F5). The optimum conditions for CL emission were investigated. The linear relationship between the relative CL intensity and the concentration of CPLX is in the range of 9.0 x 10^-9-1.0 x 10^-6 mol/l with a detection limit of 3.1 x 10^-10 mol/l. The relative standard deviation is 2.8% (n=11) for a level of 5.0 x 10^-8 mol/l. The method was applied to the analysis of CPLX in human serum and urine samples with satisfactory results. The possible mechanism for this sensitized CL reaction is also discussed.

"Determination Of Trivalent Terbium Ion In Mineral By Flow Injection Chemiluminescence"
Fenxi Huaxue 2005 Volume 33, Issue 5 Pages 647-649
Wang Xiaoli, Zhao Huichun, Li Xia, Chen Shilü

Abstract: A simple flow injection chemiluminescence(CL) analysis method for the determination of terbium in mineral sample is reported. It is based on luminescence produced by NaIO4-H2O2 CL system sensitized by [Tb(EDTA)2]-. The relative chemiluminescence intensity of the Tb3+-EDTA-NaIO4-H2O 2 system is proportional to the amount of Tb3+. The maximum CL intensity was obtained at concentration of 2.0 ? 10 -3 mol/L EDTA, 0.048% H2O2 and 1.0 x 10^-2 mol/L NaIO4. The linear range and detection limit for Tb3+ are 1.0 x 10^-7-1.0 x 10^-5 mol/L and 8.0 x 10^-9 mol/L, respectively. The relative standard deviation for 12 independent determinations of 1.0 x 10^-6 mol/L Tb3+ was 3.2%. This method was successfully applied to the determination of terbium in rare earth oxide and mine. And the mechanism of chemiluminescence was proposed.

"Flow Injection Analysis Of Sparfloxacin By Photochemical Sensitized Chemiluminescence Method"
Fenxi Huaxue 2002 Volume 30, Issue 8 Pages 920-924
Sun Chunyan, Zhao Huichun, Yi Lin, Lu Yan

Abstract: Sparfloxacin (SPFX) undergoes a photochemical reaction irradiated by ultraviolet radiation in acidic medium, and the photoproduct can form a complex with Tb3+. The complex can sensitize the chemiluminescence (CL) intensity of Ce(IV)-SO2-3. Based on the chemiluminescence reaction, a new flow injection-photochemical sensitized chemiluminescence method for the determination of SPFX was developed. The detection limit is 2.5 x 10^-8 mol/L. The relative CL intensity was linear with the concentration of SPFX in the range of 1.0 x 10^-7-1.0 x 10^-5 mol/L. The relative standard deviation for the determination of 6.0 x 10^-6 mol/L SPFX was 3.8% (n = 11). The method has been successfully applied to the analysis of SPFX in tablet and capsule. An original mechanism was proposed to explain this phenomenon.

"Terbium Sensitized Chemiluminescence Of Gatifloxacin And Its Application"
Gaodeng Xuexiao Huaxue Xuebao 2002 Volume 23, Issue 4 Pages 564-566
Lian Ning, Zhao Huichun, Sun Chunyan, Jin Linpei, Zhang Zhonglun, Zheng Yanzhen

Abstract: A selective and sensitive sensitized chemiluminescence (CL) method for the determination of Gatifloxacin(GFLX) is described. The method is based on Tb3+ sensitized chemiluminescence of the Tb3+-GFLX-Ce(IV)-SO2-3 system since CL for the binary Ce(IV)-SO2-3 system is weak, while CL is enhanced when Tb3+-GFLX is added to the Ce(IV)-SO32- system. The possible mechanism of the CL reaction may be that Ce(IV) can oxidize HSO-3 to a hydrogen-sulfite radical HSO3*, then HSO3* radicals produce S2O62-6, S2O2-6 will form the excited intermediate product SO*2. The energy of SO*2 is mainly transferred to Tb3+-GFLX, and the CL spectrum shows a characteristic emission of Tb3+. The relationship between the CL intensity and the concentration of GFLX is linear in the range of 2.0 x 10^-8-1.0 x 10^-6 mol/L, and the detection limit is 3.5 x 10^-9 mol/L. The relative standard deviation(RSD) for 11 independent determinations of 1.0 x 10^-7 mol/L GFLX was 3.2%. Common excipient starch was used in pharmaceutical preparation and most of metal ions do not interfere with the determination of GFLX. GFLX in urine can be analyzed directly after appropriate dilution of the samples, and the analytical result is satisfactory.

"Europium Sensitized Chemiluminescence Determination Of Pazufloxacin Mesylate In Urine And Serum"
Anal. Lett. 2005 Volume 38, Issue 6 Pages 971-979
X. -L. Wang; S. -L. Chen; H. -C. Zhao; L. -P. Jin; Xia Li

Abstract: A novel chemiluminescence (CL) flow injection method for the determination of pazufloxacin mesylate (PZFX) is described. It is based on CL of a KMnO 4-Na2S2O4 system sensitized by the complex [Eu(PZFX)2]3+, and shows the intensive characteristic bands of Eu3+. The optimum conditions for CL emission were investigated. Under the optimum experimental condition, the linear range is 1.0 x 10^-8-1.0 x 10^-6 mol/L and the detection limit is 2.6 x 10^-9 mol/L. The method was successfully applied to the determination of PZFX in serum and urine samples. The possible mechanism for this CL system is discussed. Copyright © Taylor & Francis, Inc.

"Determination Of Trivalent Europium Using Flow Injection Chemiluminescence Method"
Anal. Chim. Acta 2004 Volume 506, Issue 1 Pages 25-29
Shilv Chen, Huichun Zhao, Xiaoli Wang, Xia Li and Linpei Jin

Abstract: A simple flow injection chemiluminescence (CL) analysis method for the determination of europium in mineral samples is reported. It is based on luminescence produced by NaIO4-H2O2 CL system sensitized by [Eu(EDTA)]-. The relative chemiluminescence intensity of the Eu3+-EDTA-NaIO4-H2O2 system is proportional to the amount of Eu3+. The optimized experimental conditions were investigated. The linear range and detection limit for Eu3+ are 2.0 x 10^-7 to 1.0 x 10^-5 and 6.2 x 10^-8 M, respectively. The sample throughput of the method is 80 samples/h. This method was successfully applied to the determination of europium in rare earth oxides. And the mechanism of chemiluminescence is proposed.

"Europium. Sensitized Chemiluminescense Determination Of Rufloxacin"
Anal. Chim. Acta 2001 Volume 445, Issue 2 Pages 169-175
Xu Wang, Huichun Zhao, Lihua Nie, Linpei Jin and Zhonglun Zhang

Abstract: A novel chemiluminescence (CL) flow system for rufloxacin (RFX) combined flow injection analysis is presented in this paper. It is based on the energy transfer from RFX to europium(III), the intense luminescence instead of the weak CL produced by cerium(IV)-sulfurous acid-RFX CL system can be observed when Eu(III) was added to the system. A narrow and highly intense emission band at 617 nm arised from the excited-state Eu(M) was obtained. Under the optimum experimental conditions, the linear range was 2.0 x 10^-8 to 5.0 x 10^-7 M and the detection limit was 5.0 x 10^-9 M. The method has been successfully applied to determination RFX in dosage form, serum samples and urine samples. The recoveries were 95.0-104.9% for serum and urine samples.

"Determination Of Lomefloxacin By Terbium Sensitized Chemiluminescence Method"
Anal. Bioanal. Chem. 2002 Volume 374, Issue 7-8 Pages 1187-1190
Li-Hua Nie, Hui-Chun Zhao, Xu Wang, Lin Yi, Yan Lu, Lin-Pei Jin, Hui-Min Ma

Abstract: A simple, rapid and sensitive chemiluminescence (CL) method was proposed for the determination of lomefloxacin (LFX). This method is based on the fact that the weak CL from the redox reaction of Ce4+-Na2SO3 can be greatly enhanced by the complex of Tb3+-LFX. The CL intensity is directly proportional to the concentration of LFX in the range 2.0 x 10^-9 to 1.0 x 10^-5 mol L-1, and the detection limit (S/N=3) is 1.1 x 10^-9 mol L-1. This method has been applied to the detection of LFX in pharmaceutical preparation, urine and serum samples. Recoveries were in the range 95-105%. The CL mechanism of Ce4+-Na2SO3-Tb3+-LFX system was proposed to be an intermolecular energy transfer from excited SO2* to LFX and an intramolecular energy transfer from LFX to Tb3+.