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  • 1
    Electronic Resource
    Electronic Resource
    Potentiometric biosensor for riboflavin based on the use of aporiboflavin-binding protein (1987)
    s.l. : American Chemical Society
    Analytical chemistry 59 (1987), S. 2115-2118 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00144a023
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  • 2
    Electronic Resource
    Electronic Resource
    Highly sensitive determination of L-lactate and pyruvate by liquid chromatography and amperometric detection with lactate oxidase-lactate dehydrogenase coimmobilized reactor involving amplification by substrate recycling (1991)
    Weinheim : Wiley-Blackwell
    Electroanalysis 3 (1991), S. 493-497 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An amperometric flow injection system with a lactate oxidase-lactate dehydrogenase coimmobilized reactor involving amplification by substrate recycling is used as a specific postcolumn detector system in liquid chromatography, to detect L-lactate and pyruvate with high sensitivity. Both components are separated at a reversed phase column and are recycled enzymatically during the passage through the enzyme reactor in the presence of reduced nicotinamide adenine dinucleotide (NADH) and oxygen in the carrier stream. As a result of this recycling reaction, a large amount of hydrogen peroxidase is generated in the enzyme reactor which is detected amperometrically at a flow-through peroxidase electrode in the presence of hexacyanoferrate(II) as a mediator. Linear determination range is 0.2-200 pmol for both L lactate and pyruvate. The detection limit is 0.02 pmol. The relative standard deviation obtained for this system at 2 pmol L-lactate and pyruvate (n=5)is about 3.8%.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140030608
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  • 3
    Electronic Resource
    Electronic Resource
    Amperometric flow-injection analysis of purine nucleotides: Comparison of selectivity for hydrolytic cleavage of purine nucleotides (1994)
    Weinheim : Wiley-Blackwell
    Electroanalysis 6 (1994), S. 706-710 
    Details
    ISSN: 1040-0397
    Keywords: Purine nucleotide ; Flow-injection analysis: Enzyme reactor ; Hydrolase ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four hydrolases (alkaline phosphatase, apyrase, 5′-nucleotidase, and adenosine-5′-triphosphatase) are immobilized onto the controlled-pore glass, respectively. They are used as the reactor for the enzyme-catalyzed hydrolytic cleavage of purine nucleotides, in a flow-injection system based on the combined use of the following coimmobilized purine nucleoside phosphorylase-xanthine oxidase reactor and amperometric detector downstream. Four hydrolase-immobilized reactors possess interesting differences in the selectivity for the hydrolytic cleavages of purine nucleotides. The alkaline phosphatase reactor catalyzes enzymatically the complete conversion of all the purine nucleotides to the corresponding nucleosides. The apyrase reactor converts completely both nucleoside triphosphate and diphosphate to nucleoside monophosphate. The 5′-nucleotidase reactor is selective for the hydrolytic cleavage of nucleoside monophosphate to nucleoside. The analytical importance of these hydrolase-immobilized reactors is discussed for the selective detection of purine nucleotides.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140060816
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  • 4
    Electronic Resource
    Electronic Resource
    Simultaneous determination of phosphate and pyrophosphate by an amperometric flow-injection system with immobilized enzyme reactors (1993)
    Weinheim : Wiley-Blackwell
    Electroanalysis 5 (1993), S. 887-890 
    Details
    ISSN: 1040-0397
    Keywords: Enzyme reactor ; Phosphate ; Flow injection analysis ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A bioamperometric flow-injection system is proposed for the simultaneous determination of phosphate and pyrophosphate. The injected sample is split so that part passes through an immobilized inorganic pyrophosphatase reactor before passing through a coimmobilized nucleoside phosphorylase-xanthine oxidase reactor. The other portion passes only through the latter reactor. Because each channel has a different residence time, two peaks are obtained. The first peak corresponds to phosphate and the second peak to the total phosphate (phosphate plus pyrophosphate). The maximum currents of both peaks are linearly related to the concentration of phosphate and total phosphate, respectively; 20 samples per hour can be processed with an RSD 〈 1.5%.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140050926
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  • 5
    Electronic Resource
    Electronic Resource
    On-line amperometric assay of glucose, L-glutamate, and acetylcholine using microdialysis probes and immobilized enzyme reactors (1995)
    Weinheim : Wiley-Blackwell
    Electroanalysis 7 (1995), S. 1114-1117 
    Details
    ISSN: 1040-0397
    Keywords: Amperometric detection ; Microdialysis probe ; Immobilized enzyme reactor ; In vivo monitoring ; Glucose ; L-Glutamate ; Acetylcholine ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A highly selective on-line, real-time monitoring system is proposed for amperometric assay of glucose, L-glutamate, and acetylcholine. The system includes a microdialysis probe, immobilized enzyme reactor, and poly(1,2-diaminobenzene)-coated platinum electrode. The analyte in the dialysate from the microdialysis probe is enzymatically converted to produce hydrogen peroxide. The hydrogen peroxide is detected selectively at a poly(l,2-diaminobenzene)-coated platinum electrode, without any interference from oxidizable species and proteins. The present method can be successfully applied to in vitro assay of glucose and in vivo monitoring of glucose in rat brains. However, the sensitivity is not sufficient for in vivo monitoring of trace amounts of L-glutamate and acetylcholine in rat brains.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140071203
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  • 6
    Electronic Resource
    Electronic Resource
    Highly sensitive detection of L-lactate and pyruvate by amperometric flow-injection analysis based on enzymatic substrate recycling and selective detection of hydrogen peroxide (1995)
    Weinheim : Wiley-Blackwell
    Electroanalysis 7 (1995), S. 395-397 
    Details
    ISSN: 1040-0397
    Keywords: Enzyme reactor ; Substrate recycling ; Poly(1,2-diaminobenzene)film-coated electrode ; Flow injection analysis ; L-Lactate ; Pyruvate ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The poly(1,2-diaminobenzene)film-coated platinum electrode was used as an amperometric detector in a flow-injection system with the lactate dehydrogenase/lactate oxidase coimmobilized reactor involving amplification by substrate recycling. Both L-lactate and pyruvate are recycled enzymatically during their passage through the enzyme reactor in the presence of reduced nicotinamide adenine dinuceotide (NADH) and oxygen in the carrier stream. As a result, a large amount of hydrogen peroxide is generated in the enzyme reactor. The poly(1,2-diaminobenzene)-coated electrode could only selectively detect the hydrogen peroxide generated in the enzyme reactor, without an increase in the base-line current owing to the direct oxidation of NADH, because the poly(1,2-diaminobenzene) film effectively prevented NADH in the carrier stream from reaching the electrode surface and allowed only the hydrogen peroxide to penetrate into the polymerized film. In the present flow-injection analysis (FIA) system, both L-lactate and pyruvate were determined with a 400-fold increase in sensitivity compared with the unamplified responses. The detection limit was 2 × 10-9 M (20 fmol) for 10 μL sample injection.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140070418
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  • 7
    Electronic Resource
    Electronic Resource
    Microdialysis fiber enzyme electrode involving amplification by substrate recycling (1997)
    Weinheim : Wiley-Blackwell
    Electroanalysis 9 (1997), S. 950-951 
    Details
    ISSN: 1040-0397
    Keywords: Mikrodialysis fiber electrode ; Microenzyme-electrod ; NAD+/NADH sensor ; Substrate recycling ; Amplification ; Size-exclusion film ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A microdialysis fiber electrode involving amplification for the NAD+/NADH couple is described. The electrode contains glucose-6-phosphate dehydrogenase, lactate dehydrogenase and lactate oxidase held stationary within its cavity, with a platinum fiber coated with poly(1,2-diaminobenzene) film as a working electrode and a silver/silver chloride fiber as a reference electrode. Both NAD+ and NADH are recycled enzymatically in the presence of an excess of glucose-6-phosphate and pyruvate in the measuring buffer solution. As a result, a large amount of L-lactate produced in the electrode cavity is converted to pyruvate to produce hydrogen peroxide, which can be detected ampero metrically at the platinum fiber with a size-exclusion film. Both NAD+ and NADH were detected with a 25-fold increase in sensitivity compared with the unamplified responses. The detection limit was 1 × 10-7 M.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140091217
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  • 8
    Electronic Resource
    Electronic Resource
    An electroanalytical method for estimation of fish freshness using a flow-injection system with some immobilized enzyme reactors (1989)
    Weinheim : Wiley-Blackwell
    Electroanalysis 1 (1989), S. 173-176 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A flow-injection system is proposed for the estimation offish freshness. The 5′-adenylic acid deaminase reactor, alkaline phosphatase reactor, and nucleoside phosphorylase-xanthine oxidase coimmobilized reactor were incorporated at fixed positions in a flow system, which was based on the splitting of the flow after sample injection and subsequent confluence before reaching the peroxidase electrode. Because each channel has a different residence time, two peaks were obtained. The first peak corresponded to the total of hypoxanthine and inosine, and the second peak to the total of hypoxanthine, inosine, inosine-5′-monophosphate, and adenosine-5′-monophosphate. The index of fish freshness, K, is estimated by \documentclass{article}\pagestyle{empty}\begin{document}$$ K = (S_2 /S_1)(i_1 /i_2)\,{\rm x}\,{\rm 100} $$\end{document} where s1 and s2 represent the sensitivity (nA mM-1) and i1 and i2 represent the peak current (nA) of the first and second peaks, respectively. The measurements could be performed at a rate of 15 samples per hour with satisfactory precision.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140010214
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  • 9
    Electronic Resource
    Electronic Resource
    Amperometric determination of lactose in human and cow's milk using a flow-injection system with some immobilized enzyme reactors (1989)
    Weinheim : Wiley-Blackwell
    Electroanalysis 1 (1989), S. 413-416 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A bioelectrochemical flow-injection system is proposed for the determination of lactose in milk from humans and cows. The system includes an amperometric flow-through platinum electrode to measure hydrogen peroxide, which was enzymatically generated by injecting a 10-μL sample into the packed-bed reactors of immobilized β-galactosidase and glucose oxidase that are incorporated in series in the flow line. Because the presence of glucose interfered with the measurement of lactose, a precolumn packed with coimmobilized glucose oxidase and catalase was positioned just before the two immobilized enzyme reactors to remove the glucose from the milk. The peak current was linearly related to the lactose concentration between 0.01 and 2.0 mM. The determinations of lactose in milk could be performed at a rate of 60 samples/h with satisfactory precision (less than 0.8% RSD) and no pretreatment except for the sample dilution.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140010506
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  • 10
    Electronic Resource
    Electronic Resource
    Amperometric flow-injection analysis of L-glutamate using an immobilized enzyme reactor: Amplification by substrate recycling (1990)
    Weinheim : Wiley-Blackwell
    Electroanalysis 2 (1990), S. 563-565 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An amperometric flow injection system with an immobilized enzyme reactor that gives responses amplified by substrate recycling was employed for the highly sensitive determination of L-glutamate. An L-glutamate oxidase/glutamic-pyruvic transaminase coimmobilized reactor was incorporated at fixed positions in a flow system. In the presence of sufficient amounts of L-alanine and oxygen in the carrier solution, L-glutamate was repeatedly converted to 2-oxoglutarate by L-glutamate oxidase, and the 2-oxoglutarate produced was subsequently converted back to L-glutamate by glutamic-pyruvic transaminase during the passage through the enzyme reactor. As a result of this recycling reaction, a large amount of hydrogen peroxide was produced in the reactor and could be detected amperometrically at a downstream platinum detector. L-Glutamate was determined with a 20- to 30-fold increase in sensitivity compared to the unamplified responses. The detection limit was 1 pmol of L-glutamate.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140020711
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