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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In vitro monitoring

Classification: Feature -> In vitro monitoring

Citations 6

"Flow Injection Analysis-fluorescence Detection For The In Vivo On-line Determination Of Calcium In Blood With Microdialysis Sampling"
Anal. Chim. Acta 2000 Volume 419, Issue 2 Pages 175-184
Yuming Huang, Zhujun Zhang, Jiagen Lv and Hua Cheng

Abstract: Due to its high selectivity for calcium, calcein can be used as fluorescent indicator for the sensitive determination of calcium. A flow injection on-line microdialysis system for in vivo monitoring of calcium in blood is developed. A microdialysis probe, implanted in the vein of rabbit, was perfused with perfusate at a flow rate of 5 µl/min. The concentration of calcium in the dialysate was determined on-line with a flow injection fluorescence system. The dialysate sample volume was about 15 µl. The system was linearly related to the concentration of calcium in the range 0-80 µg/ml (r2=0.9968) with a detection limit (3s) of 0.01 µg/ml and the sample throughput of 20 h-1. RSD was <5% (n=11). The validation of using the no net flux method of quantitative microdialysis to measure concentration of calcium was evaluated in vitro and in vivo. The accuracy of this method was tested in vitro under steady-state conditions for three test solutions containing known concentration of calcium. The estimated concentration of calcium were 32±2, 42±2, and 49.5±0.9 µg/ml (mean±RSD) in agreement with the actual concentrations of calcium in the test solutions which were 30, 40 and 50 µg/ml, respectively. In vivo, the estimated basal of calcium in dialysis sample from probe in the test animals blood was 33 µg/ml.
Calcium Rabbit Blood Fluorescence

"Aluminum Fractionation In A Simulated Rat Stomach: An In Vitro Study"
Analyst 1995 Volume 120, Issue 3 Pages 713-720
Lars-G&ouml;ran Danielsson, Anders Spar&eacute;n and Anders Wicklund Glynn

Abstract: The conditions in a rat stomach were simulated using an in vitro system and the effects of various parameters such as pH, feed content and the presence of enzymes on the solubility and distribution of Al species were studied. Experiments were performed at 37°C using ground rat feed, at a fixed pH and with hog pepsin A as the enzyme. Al (4 mg/l) was added and the mixture was stirred for 2 h. After centrifugation, the supernatant solution was filtered and analyzed for Al species. Quickly-reacting Al was determined by flow injection spectrophotometry by a modification of the method described by Clarke et al. (Int. J. Environ. Anal. Chem., 1992, 48, 77). Total dissolved Al, Fe and P were determined by ICP-AES at 308.2, 238.2 and 214.9 nm, respectively. Possible reasons for the observed distribution of the Al species are discussed. The pattern of the in vitro results was confirmed by measurements in pooled rat stomachs from in vivo experiments. The results highlighted the importance of fractionation measurements in bioavailability studies of Al.
Aluminum Stomach Spectrophotometry Sample preparation

"Determination Of Plasma Oxalate Concentrations Using An Enzyme - Bioluminescent Assay. 2. Co-immobilization Of Bioluminescent Enzymes And Studies Of In Vitro Oxalogenesis"
Clin. Chim. Acta 1989 Volume 179, Issue 1 Pages 97-108
I. S. Parkinson, S. M. Channon, C. R. V. Tomsona, L. R. Adonai, M. K. Ward*,* and M. F. Laker*

Abstract: Sample or standard solution (4 µL) was incubated with oxalate decarboxylase solution for 30 min at room temperature Formate dehydrogenase was added and incubation was continued for 60 min. A portion of the reaction mixture was transferred to a continuous-flow system for determination of NADH by bioluminescence. The reaction mixture was mixed with a bioluminescent solution of 80 mM NaH2PO4 - trisodium citrate (pH 7.0) containing 30 mM dithiothreitol, 120 µM-flavine mononucleotide and 300 µM-decanal, and this mixture was then passed through a flow-cell containing gel-immobilized NAD(P)H dehydrogenase (FMN) and luciferase enzymes. Luminescence was monitored with a luminometer. The limit of detection was 0.8 µM-oxalate (I). The intra-batch coefficient of variation were 5.2 and 3.8% at 18 and 60 µM-I, respectively. Recovery was 100.7%. There was no interference by 1 mM ascorbate.
Oxalate Blood Plasma Bioluminescence Clinical analysis

"A Continuous-flow System For Measuring In-vitro Oxygen And Nitrogen-metabolism In Separated Stream Communities"
Freshw. Biol. 1991 Volume 26, Issue 3 Pages 495-506
C. PRAHL, E. JEPPESEN, K. SAND-JENSEN, T. MOTH-IVERSEN

Abstract: 1. This paper describes a continuous-flow system that we have used extensively for measurement of oxygen exchange and nitrogen transformations in different communities of lowland streams, i.e. the water, the sediment, and the macrophyte-biofilm community. The system, which is set up on the stream bank, consists of several macrophyte and sediment chambers equipped with a double-flow system that ensures an internal water velocity close to that in the stream and which, by continuously renewing the water, mimics diel fluctuation in stream temperature and water chemistry. Water temperature and dissolved oxygen are measured continuously and the data stored on magnetic tape. Water samples are collected in a refrigerator and analyzed using standard chemical procedures. 2. The application of the system is illustrated using results obtained during a 2-day summer experiment in a shallow macrophyte-rich stream. The biological processes in the stream were mainly associated with the macrophyte-biofilm community and the sediment, those in the water being negligible. Oxygen release was confined to the macrophyte-biofilm community, the sediment consuming oxygen both by day and by night. Whole-system gross production and dark respiration occurred at similar rates (6-7g O2 m-2 day-1), net balance being about zero. Inorganic nitrogen was consumed both by the sediment and to a greater extent by the macrophytes, the diel average consumption being 1g N m-2 day-1. 3. The sum of the activity in the macrophyte and sediment chambers corresponded to the overall activity of the stream section as determined by upstream/downstream mass balance. This indicates that the results obtained with the continuous-flow chambers realistically describe the oxygen and the nitrogen metabolism of the stream.
Nitrogen Oxygen Water

"Flow Injection Analysis Using Ion-sensitive Field Effect Transistors. A Model System For Discrete Assays And Continuous In Vitro Monitoring Of PH And PCa"
Scand. J. Clin. Lab. Invest. 1982 Volume 161, Issue 1 Pages 35-41
Ruzicka, J.;Ramsing, A.

Abstract: A miniaturized flow injection system yields an instant readout and requires microlitre volumes of sample and reagent solutions. Using electrode measurement as an example it is shown that the difference between discrete assays and continuous monitoring becomes so small that the same apparatus will eventually perform both functions.
Calcium pH Clinical analysis Field effect transistor Electrode

"Application Of Flow Injection Analysis To The Studies Of In Vitro Enzymic Degradation And Release Of Nanoparticle Or Nanocapsule"
Yaoxue Xuebao 1994 Volume 29, Issue 12 Pages 925-928
Deng, Y. H.; Li, H. Q.; Luo, X. (SFS)

Abstract: Flow injection analysis (FIA) was applied to study the in vitro release of 5-fluoro-2'-deoxyuridine (FUdR) from solution (I), FUdR-nanoparticle (II) , FUdR-ester-prodrug-nanocapsule (III) and the enzymatic degradation of III with liver, spleen or lung extract. The results showed that the release rate of FUdR from II was slowed down, while the amount of drug released from III was small. It was also confirmed that III could be degraded in the solution containing liver, spleen or lung extract, the major location for the degradation of III was in the liver. A new application of FIA to the pharmaceutical field was developed.
Enzymes Biological Pharmaceutical