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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Hui Chen

Abbrev:
Chen, H.
Other Names:
Address:
Department Chemistry, NW Normal University, Lanzhou 730070, China
Phone:
NA
Fax:
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Citations 10

"An Online Determination Of Chlorine Dioxide Using Chlorophenol Red By Gas Diffusion Flow Injection Analysis"
Lab. Rob. Autom. 1999 Volume 11, Issue 3 Pages 157-161
Hui Chen, Yanjun Fang, Li Yuan, Taicheng An

Abstract: An an-line determination of chlorine dioxide (ClO2) in potable water using chlorophenol red (CPR) by gas diffusion flow injection analysis (FIA) was investigated in the presence of various chlorinated species that can occur under normal water-treatment conditions. A gas diffusion membrane is used to separate the donor (sample) stream from the acceptor (detecting) stream (the donor stream transports the sample stream to the membrane separate device, and the acceptor stream collects all of the penetrated analytes and transports quantitatively to the detector) and makes it possible for this method to eliminate interference from metal ions, as well as other oxychlorinated compounds such as chlorite and chlorate. The system is more selective for chlorine dioxide than chlorine. The linear range of ClO2 concentration is 0-0.5 mg . mL-1 with a detection limit of 0.02 µg . mL-1 (S/N = 3) and a sampling frequency of 50 h -1.

"Simultaneous Spectrophotometric Determination Of Nitrite And Nitrate In Water Samples By Flow Injection Analysis"
Int. J. Environ. Anal. Chem. 2000 Volume 76, Issue 2 Pages 89-98
Hui Chen; Yanjun Fang; Taicheng An; Kun Zhu; Jinren Lu

Abstract: An automatic direct spectrophotometric method for the simultaneous determination of nitrite and nitrate by flow injection analysis has been developed. The method is based on the reaction of nitrite and nitrate with the spectrophotometric reagent N-phenylanthranilic acid in sulfuric acid medium (pH=0.4 similar to 0.6) to form the same color products while the absorbance is measured at 410 nm. This method has the advantage of direct determination of nitrite and nitrate and without reducing nitrate to nitrite as other reported methods. Various analytical parameters, such as flow rate, sample size, effect of acidity(pH), reagent concentration and interfering species were studied. The detection limit is 2.5 ng mL-1 for nitrite and 12 ng mL-1 for nitrate. Up to 35 samples per hour can be analyzed with a relative precision of ~0.1-2%.

"Flow-injection Chemiluminescence Determination Of Trace Calf Thymus DNA"
Chin. Chem. Lett. 2003 Volume 14, Issue 10 Pages 1051-1053
Min ZHOU, Yong Jun MA, Xiao Yong JIN, Xiu Lan TENG, Zi Yu ZHANG, Hui CHEN

Abstract: A flow injection procedure for the determination of calf thymus DNA (CT DNA) over the range 2.1 x 10^-6 - 2.1 x 10^-1 µg mL-1 is described, based on measurement of the enhanced chemiluminescence emission of rhodamine B-Ce(IV) system, activated by imidazole-HCl buffer solution. This method is highly sensitive, with the linearity range broadened to five orders of magnitude. It has been applied to determine CT DNA in synthetic sample with satisfactory results.

"Determination Of Ceftriaxone Sodium In Pharmaceutical Formulations By Flow Injection Analysis With Acid Potassium Permanganate Chemiluminescence Detection"
Anal. Sci. 2006 Volume 22, Issue 1 Pages 183-186
Deyi Zhang, Yongjun Ma, Min Zhou, Li Li And Hui Chen

Abstract: Based on the chemiluminescence (CL) emission generated from the oxidation of ceftriaxone sodium alkali hydrolysate by potassium permanganate in polyphosphoric acid (PPA), a novel determination method for ceftriaxone sodium was developed by using a flow-injection technique. The calibration curve appears to be linear in the range between 0.05 and 100 µg mL-1 with a detection limit (3 s) of 25 ng mL-1, and a relative standard deviation (RSD) of 0.6% for eleven replicate determinations of 5.0 µg mL-1 ceftriaxone sodium. The proposed method has been successfully utilized for the determination of ceftriaxone sodium in pharmaceutical formulations, while the chemiluminescence reaction mechanisms were investigated.

"Flow Injection Catalytic Spectrophotometric Determination Of Trace Amounts Of Nitrite"
Anal. Lett. 1999 Volume 32, Issue 14 Pages 2887-2897
Hui Chen; Yan-jun Fang; Tai-cheng An; Xing-long Jin

Abstract: A flow injection catalytic spectrophotometric method is proposed for the determination of nitrite based on its catalytic effect on potassium bromate oxidation of acridine orange in phosphoric acid medium. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance of acridine orange at 491.5 nm coupling with the stopped-flow technique. The calibration curve was linear between 3.4 and 65 ng/mL, and the detection limit was 2.2 ng/mL. Up to 30 samples can be analyzed per hour with a relative precision of ~1.9%. The proposed method was successfully applied to the determination of nitrite in waters and food samples with satisfactory results.

"The Determination Of Manganese(II) In Water By Reversed Flow Injection Spectrophotometry"
Anal. Lett. 1999 Volume 32, Issue 4 Pages 787-797
Hui Chen; Dongbin Wei; Taicheng An; Yanjun Fang

Abstract: This paper describes a reversed now injection spectrophotometric method for determination of manganese(II) at low levels. A new chromogenic system TCMOPPH2-Cd(II)-imidazole has been set up using a novel synthetic chromogenic reagent meso-tetra[4-(carboxymethylenoxy)phenyl]porphyrin [TCMOPPH2] by a substitution reaction of Mn(II) and Cd(II)-TCMOPP complex. The linear range extends from 0.01 to 1.75 mg.L-1 with a sampling frequency of 90 h-1. Co(II), Cu(II), Cr(III) and Fe(II) exert no interference until their concentrations are up to 30, 32, 15 and 23 times of that of Mn(II), respectively. The proposed method is proved to be simple, sensitive and suitable for online determination of Mn(II), and it has been used in analysis of Mn(II) in water samples of Liaohe Oil Field water treat plant during the on spot purification. The detection limit was 2.8 µg.L-1.

"Flow-injection Chemiluminescence Assay For Ultra-trace Determination Of DNA Using Rhodamine B-Ce(IV)-DNA Ternary System In Sulfuric Acid Media"
Anal. Chim. Acta 2004 Volume 501, Issue 1 Pages 25-30
Yongjun Ma, Min Zhou, Xiaoyong Jin, Ziyu Zhang, Xiulan Teng and Hui Chen

Abstract: A novel flow-injection chemiluminescence method for the determination of DNA at ultra-trace level has been established. In 0.8 M sulfuric acid media, the chemiluminescence of the rhodamine B-cerium (IV) or Ce(IV) system is enhanced by DNA, activated previously by imidazole-HCl buffer solution (pH 7.0). The enhanced intensity of chemiluminescence is in proportion to log DNA concentration 1.0 x 10^-8 to 0.1?gml-1 for herring sperm DNA and 2.0 x 10^-6 to 0.2?gml-1 for calf thymus DNA with 3? detection limits of 8.3 x 10 -9?gml-1 for herring sperm DNA and 3.5 x 10 -7?gml-1 for calf thymus DNA, respectively. The relative standard deviation for 1.0 x 10^-4?gml-1 herring sperm DNA was 0.99% and 2.0 x 10^-3?gml-1 for calf thymus DNA was 1.1% (n=11). Using the optimized system, DNA contents in six synthetic samples has been determined with recoveries of 99.5-109.0%. The possible mechanism has also been studied in this paper. © 2003 Elsevier B.V. All rights reserved.

"Chemiluminescence Behavior Based On Oxidation Reaction Of Rhodamine B With Cerium(IV) In Sulfuric Acid Medium"
Anal. Chim. Acta 2003 Volume 489, Issue 2 Pages 173-181
Yongjun Ma, Xiaoyong Jin, Min Zhou, Ziyu Zhang, Xiulan Teng and Hui Chen

Abstract: The chemiluminescence (CL) of the rhodamine B (RhB)-cerium(IV) system was investigated by flow-injection. Rhodamine B was suggested to be a suitable chemiluminescent reagent in acidic conditions. When the concentration of rhodamine B was 100 mg L-1 and cerium sulfate was 1.6 mmol L-1 in sulfuric acid, the chemiluminescent intensity was found to be highest by using 0.3 mol L-1 sulfuric acid as a carrier solution. The particular chemiluminescent system could tolerate such distinct acidic environments that it was utilized for detecting many compounds that are stable in acidic solutions. Furthermore, by virtue of IR, UV-Vis and luminescence spectroscopic measurements, the chemiluminescent behavior of rhodamine B was studied and a possible mechanism for this chemiluminescent reaction was proposed. The emitter was affirmed to be a radical species due to one of the oxidation products of RhB; the chemiluminescent emissive wavelength was about 425 nm.

"Chemiluminescence Determination Of Ultramicro DNA With A Flow-injection Method"
Anal. Chim. Acta 2003 Volume 478, Issue 1 Pages 31-36
Hui Chen, Min Zhou, Xiaoyong Jin, Yumin Song, Ziyu Zhang and Yongjun Ma

Abstract: A high sensitive flow-injection chemiluminescence method for determination of calf thymus DNA and herring sperm DNA has been developed. The method is based on the chemiluminescence reaction of Rhodamine B-cerium(IV)-thermally denatured DNAs in sulfuric acid media. The proposed procedure allows quantitation of DNAs in the range 2.6 x 10^-5 to 0.26 µg ml-;1 for calf thymus DNA and 5.0 x 10^-8 to 5.0 x 10^-5 µg ml-;1 for herring sperm DNA with correlation coefficients 0.9998 and 0.9996 (both n=11), respectively. The detection limits (3s) are 6.5 x 10^-6 µg ml-;1 for calf thymus DNA and 4.3 x 10^-8 µg ml-;1 for herring sperm DNA. The possible mechanism of chemiluminescence in the system is discussed.

"Flow Injection Chemiluminescence Determination Of Ascorbic Acid By Use Of The Cerium(IV)-Rhodamine B System"
Anal. Chim. Acta 2002 Volume 464, Issue 2 Pages 289-293
Yongjun Ma, Min Zhou, Xiaoyong Jin, Baozhu Zhang, Hui Chen and Naiyun Guo

Abstract: A highly sensitive flow injection (FI) method with chemiluminescence (CL) detection is used for the determination of L-ascorbic acid. The method is based on the CL reaction of Rhodamine B with cerium(IV) in sulfuric acid media. L-Ascorbic acid is suggested to be a catalyst utilized in the energy-transferred excitation process. The proposed procedure allows quantitation of L-ascorbic acid in the range 3.8 x 10^-13 to 1.0 x 10^-10 mol L-1 with a correlation coefficient of 0.9998 (n = 5) and relative standard deviation (RSD) of 0.92% (n = 11) at 1.0 x 10^-11 mol L-1. The detection limit (3 x blank) was 1.0 x 10^-13 mol L-1. The method is successfully used to determine L-ascorbic acid in fresh vegetables. The possible mechanism of the chemiluminescence in the system is discussed. (C) 2002 Elsevier Science B.V. All rights reserved.
Ascorbic acid