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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Jong Il Rhee

Abbrev:
Rhee, J.I.
Other Names:
Jong-Il Rhee
Address:
Bioprocess Technology Laboratory, Faculty of Chemical Engineering, Biochemical Engineering Department, Chonnam National University, 300 YongBong-dong, 505-757 KwangJu, South Korea
Phone:
+82-625301847
Fax:
+82-625301849

Citations 5

"Sequential Injection Analysis System For On-line Monitoring Of L-cysteine Concentration In Biological Processes"
Talanta 2005 Volume 68, Issue 2 Pages 187-192
Seung-Hyun Lee, Ok-Jae Sohn, Yong-Sik Yim, Kyung-Ah Han, Gi Woo Hyung, Sung Hyo Chough and Jong Il Rhee

Abstract: A sequential injection analysis (SIA) system was developed to monitor the concentration of l-cysteine in biological processes on-line. It is based on the redox reaction of l-cysteine with iron(III) in the presence of 1,10-phenanthroline (phen) and the detection of the red-iron(II)-phen complex with a spectrophotometry. The system was fully automated using software written in the LabVIEW? development environment. A number of system variables such as the flow rate of the carrier buffer solution, the volume ratio of the sample to the reagents, and the reaction coil length, etc., were evaluated to increase the sensitivity and performance of the SIA system. Under partially optimized operating conditions the performance of the SIA system was linear up to a concentration of l-cysteine of 1 mM (R2 = 0.998) with a detection limit of 0.005 mM and a sample frequency of 15 hr-1. The SIA system was employed to monitor the concentration of l-cysteine on-line in a continuously stirred reactor and a fermentation process of Saccharomyces cerevisiae. The on-line monitored data were in good agreement with the off-line data measured by a HPLC with a fluorescence detector (n = 15, R2 = 09899). © 2005 Elsevier B.V. All rights reserved.

"Flow Injection Analysis System For Monitoring Of Succinic Acid In Biotechnological Processes"
Talanta 2005 Volume 65, Issue 1 Pages 185-191
Ok-Jae Sohn, Kyung-Ah Han and Jong Il Rhee

Abstract: In this study, a flow injection analysis (FIA) system using a cartridge of immobilized isocitrate lyase (ICL) and isocitrate dehydrogenase (ICDH) was developed to monitor the concentrations of succinic acid in biotechnological processes. The ICL and ICDH immobilized on VA-Epoxy Biosynth E3-carrier had a good operational lifetime (up to 24 h) and storage stability (up to 30 days). The FIA system with the immobilized ICL/ICDH cartridge was characterized with respect to the factors affecting the activity of the immobilized enzymes, such as pH of carrier solution, temperature, sample matrix, etc. Optimal pH value of the immobilized enzymes was slightly shifted in the alkaline range, i.e. 9.0. Some components such as 10 g L-1 lactose, 3 g L-1 malate and 3 g L-1 oxaloacetate in sample solution had significant activating effects (more than 10%) on the response of the FIA system. But the activity of the immobilized ICL and ICDH was not largely influenced by some components like imidazole (1 mM), sodium azide (10 mM) and semicarbazide (2 g l-1) added to carrier buffer solution. The FIA system with an enzyme cartridge was applied to on-line monitor the concentrations of succinic acid in a continuously stirred reactor and a fermentation process of immobilized Escherichia coli, and showed good sensitivity and reliability of the FIA system developed in this work. © 2004 Elsevier B.V. All rights reserved.

"Flow Injection Sandwich ELISA For Bioprocess Monitoring"
J. Autom. Methods Manag. Chem. 1999 Volume 21, Issue 4 Pages 121-125
JONG IL RHEE, JÖRG HAGEDORN, THOMAS SCHEPER, and KARL SCHÜGERL

Abstract: A fully automated flow injection immunoassay based on sandwich enzyme-linked immunosorbent assay (ELISA) is described for the model system: protein G-sepharose, rabbit IgG and horseradish peroxidase (HRP)-labelled protein A. After injecting rabbit IgG and HRP-labelled protein A into a cartridge containing protein G-sepharose sequentially, a mixture of hydrogen peroxide and the redox indicator, 2.2-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) is passed through the cartridge. The HRP-labelled protein A bound in the cartridge is directly proportional to the concentration of rabbit IgG. The color variation of ABTS caused during the reaction between HRP and H2O2 in the cartridge is detected photometrically. The whole assay procedure is controlled and evaluated by a computer. Rabbit Ige and HRP-labelled protein A are also detected by a fluorometer, which is introduced into the flow system. In the flow injection sandwich ELISA, the slope of the calibration curve is 0.4491 in the range of 0 and 300 µg mL-1 rabbit IgG, while it is 0.1274 in the heterogeneous immunoassay. So the flow injection sandwich ELISA system is found to be more sensitive than a heterogeneous immunoassay for the monitoring of the model protein.

"Flow Injection System For On-line Monitoring Of Fumaric Acid In Biological Processes"
Anal. Chim. Acta 2003 Volume 499, Issue 1-2 Pages 71-80
Jong Il Rhee and Ok-Jae Sohn

Abstract: A flow injection system has been developed for monitoring fumaric acid in biological processes by using fumarase and malic dehydrogenase immobilized on VA-Epoxy Biosynth E3-carrier. An immobilized fumarase and malic dehydrogenase reactor had a good operational lifetime (up to 18 h) and storage stability (up to 10 days). The flow injection analysis (FIA) system with the immobilized enzymes cartridge was characterized according to the factors affecting the activity of the immobilized enzymes, such as pH, temperature, sample matrix, etc. The optimal pH value of the immobilized enzymes was slightly shifted in the alkaline range, i.e. 9.0. Some components such as 1 mM imidazole, 5 mM sodium azide and 2 g L-1 semicarbazide in a carrier buffer solution had significant inhibitory or activating effects on the response of the FIA system. But many components in the sample solution had no significant effects on the activity of the immobilized enzymes, except in the case of the 2 g L-1 acetate sample. The linear concentration ranges of fumaric acid were investigated by changing the volumetric packing ratio of two immobilized enzymes in a cartridge. The cartridge with a 1:1 packing ratio had a linear concentration range of 0.05-0.3 g L-1 with a correlation coefficient (r2) of 0.996, while the enzyme cartridge with a 1:2 packing ratio (or 1:4 packing ratio) had 0.1-0.6 g L-1 with r2=0.998 (or 0.3-1.2 g L-1 with r2=0.996). The FIA system utilizing the enzyme cartridge has been applied in order to monitor on-line the concentrations of fumaric acid in a few biological processes, i.e. a continuously stirred reactor and a cultivation process of Rhizopus oryzae Korean Collection for Type Cultures 6946.

"Development Of Xylitol Oxidase-based Flow Injection Analysis For Monitoring Of Xylitol Concentrations"
Anal. Chim. Acta 2002 Volume 456, Issue 2 Pages 293-301
J. I. Rhee, M. Yamashita and Th. Scheper

Abstract: A flow injection method for monitoring xylitol was developed using xylitol oxidase (XYO) immobilized on a VA-Epoxy Biosynth E3-support. The immobilized XYO cartridge had a good operational lifetime (up to 24 h) and storage stability (up to I month). The XYO-FIA system with an oxygen electrode was investigated systematically regarding the factors that can affect enzyme activity, such as pH, reaction temperature, carrier solution and sample matrix. In order to attain high activity of the immobilized XYO, potassium phosphate solution (I M) with 0.5 g L-1 Triton X-100 adjusted to pH 8.5 was used as the carrier solution. Sample matrix effects on the immobilized XYO were also investigated. High concentrations of some components (arabinose, 20 g l-1; xylose, 30 g l-1; NaCl, 30 g l-1) in the sample had significant inhibitory effects on the response of the XYO-FIA system. The performance of the XYO-FIA system was tested by using different sample injection volumes (75-250 µL) and carrier flow rates (0.7-2.0 mL min-1).
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