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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Confluence point

Classification: Manifold component -> Confluence point

Citations 8

"A Flow Injection Manifold Based On Splitting The Sample Zone And A Confluence Point Before A Single Detector Unit"
Anal. Chim. Acta 1984 Volume 165, Issue 1 Pages 217-226
A. Fernández, M. A. Gómez-Nieto, M. D. Luque de Castro and M. Valcárcel

Abstract: The injected sample is divided into sub-samples which pass through reactors with different characteristics. A two-peak output is obtained as a result of the different reaction times of the sub-samples. The behavior agrees with theoretical predictions. Geometric and hydrodynamic characteristics are used in expressions that allow the splitting ratio of the injected sample to be predicted.

"Confluent Streams In Flow Injection Analysis"
Anal. Chim. Acta 1987 Volume 198, Issue 1 Pages 153-163
E. A. G. Zagatto, B. F. Reis, M. Martinelli, F. J. Krug, H. Bergamin F° and M. F. Gine

Abstract: The contribution of the merging of streams to sample dispersion in flow injection analysis is discussed. Design guidelines are given in relation to sample concentration, injection volume, flow rate and the position of the confluence in relation to the injection port.

"Effects Of Manifold Components On Peak Profiles In Flow Injection Analysis"
Anal. Chim. Acta 1989 Volume 220, Issue 1 Pages 293-297
H. Wada, Y. Sawa, M. Morimoto, T. Ishizuki and G. Nakagawa

Abstract: The effects of the types of pumps and mixing coils, and the manner of merging the streams, on peak profiles were investigated. Four reciprocating pumps, three peristaltic pumps, single and double coils with helix diameter of 0.4 to 3 cm, and two types of mixing joint were examined on the basis of the reactions of Cu(II) and Ni(II) with 5-[(sulfomethyl)amino]-2-(2-thiazolylazo)-p-toluic acid (cf. Ibid., 1986, 179, 181). When pumps yielding small pulsations and double coils with small helix diameter were used, well-defined and reproducible peaks were obtained, and the effects of mixing joints were small.

"Optimization Of Confluent Mixing In Flow Injection Analysis"
Anal. Chem. 1989 Volume 61, Issue 9 Pages 973-979
Optimization of confluent mixing in flow injection analysis

Abstract: Various T-pieces for mixing streams in flow injection analysis are compared and recommendations for optimization of mixing are given in relation to the system configuration. The effects of angle of confluence, viscosity difference between streams and flow rate on mixing time and length are evaluated. Coiled or knotted reactor systems provide more rapid mixing of liquids of unequal viscosity than straight or curved reactors. In a straight-line system, mixing length is linearly proportional to flow rate, and for a 90°C T-piece mixing time is independent of flow rate.

"Design Of Coaxial Segmentors For Liquid-liquid Extraction/flow Injection Analysis"
Anal. Chem. 1990 Volume 62, Issue 18 Pages 2026-2032
Vlastimil Kuban, Lars Goeran Danielsson, and Folke Ingman

Abstract: Five coaxial segmentors of different geometries and materials were tested in a continuous liquid - liquid extraction system with computer controlled photometric detection to measure transparency directly across the stream. A confluence chamber made of a glass tube with a conical PVDF insert and an all glass segmentator with a conical outflow channel gave the best results.
Spectrophotometry Sample preparation

"Amperometric Flow Injection Biosensor System For The Simultaneous Determination Of Urea And Creatinine"
Anal. Sci. 1992 Volume 8, Issue 6 Pages 845-850
C.-S. RUI, K. SONOMOTO and Y. KATO

Abstract: A single-channel and a dual-channel flow injection system are described and illustrated. The method involved the urease-catalyzed hydrolysis of urea or the creatinine deiminase-catalyzed hydolysis of creatinine to yield NH3, and amperometric detection of the NH3 via coupled enzymatic reactions in which (i) 2-oxoglutarate was reduced to L-glutamate and H2O2 in the presence of NH4+, NAD(P)H and glutamate dehydrogenase, and (ii) the L-glutamate was re-oxidized in the presence of glucose oxidase; the consumption of O was detected with an O electrode. Each of the enzymes was immobilized on modified controlled-pore glass and packed into a glass tube for use in the flow systems. With use of the dual-channel system to determine urea and creatinine simultaneously, the response was rectilinear from 0.1 to 5 mM analyte, and the coefficient of variation (n = 12) were 5%. A flow injection biosensor system was developed for the simultaneous assay of urea and creatinine, with a single injection and one detector. The amperometric detection of urea or creatinine was based on coupled reactions of three sequentially aligned enzyme reactors, urease or creatine deiminase, glutamate dehydrogenase and glutamate oxidase. Ammonia produced by the enzymatic hydrolysis of urea or creatinine was converted to glutamate, and the oxygen consumption due to the oxidation of glutamate by glutamate oxidase was detected with an oxygen electrode. A split and confluence of the flow stream between the injector and the glutamate dehydrogenase reactor resulted in a two-channel system. Double-peak recording was achieved by putting a delay coil at one of the two channels. The system gave linear calibration curves over a range of 0.1-5.0 mM for both urea and creatinine. The assay procedure is simple and one run can be completed within 3 min. The system was reproducible within 5% of the relative standard deviation.
Urea Creatinine Amperometry Sensor

"Factors Affecting Detection Limit In Flow Injection Solution Spectrophotometry"
Anal. Proc. 1988 Volume 25, Issue 3 Pages 89-90
Andrew B. Marsden, Julian F. Tyson

Abstract: Strategies for minimization of baseline noise in flow injection - spectrophotometric systems are discussed and tested. Devices used included dampers to lessen pump roller noise, optimized design of the confluence junction of merging streams, and the introduction of intervening mixing stages, e.g., a packed-bed reactor and/or a reaction coil between the noise sources and the detector. Best results were achieved with packed-bed and open-tube coil reactors both included between the confluence point and the detector.
Chloride Spectrophotometry

"Design Of Manifolds For Flow Injection Solution Spectrophotometry"
Anal. Proc. 1989 Volume 26, Issue 2 Pages 51-52
X. Wang, A. B. Marsden, A. G. Fogg, J. F. Tyson

Abstract: Details are given of a double-line manifold for the determination of Cl- by flow injection analysis, in which a delay coil is utilized to remove interference caused by valve switching, and noise due to pump rollers and inhomogeneous mixing at the confluence point is decreased with use of pulse dampers and packed-bed and open-tubing reactors, respectively. Detection limits were from 4.5 to 8 ppb of Cl-. The design is also described of a single-line manifold for the iodimetric determination of SO32-; the detection limit was 80 ppb.
Chloride Sulfite Spectrophotometry