Differential pulse polarographic determination of citric acid with a soluble enzyme preparation

Hasebe, Kiyoshi; Hikima, Satoshi; Kakizaki, Teiji; Yoshida, Hitoshi

doi:10.1007/bf00572610

Cited by 10 publications

(2 citation statements)

References 11 publications

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“…By reaction with citrate (CIT) lyase and oxaloacetate decarboxy-lase, the analyte is converted into pyruvic acid, which is subsequently determined by differential pulse polarography [20]. Alternatively, pyruvic acid is made to react with pyruvate oxidase for a succeeding ampero-metric quantification [21][22][23].…”

Section: Introductionmentioning

confidence: 99%

Citrate selective electrodes for the flow injection analysis of soft drinks, beers and pharmaceutical products

Ribeiro¹,

Matos²,

Sales³

et al. 2002

Analytica Chimica Acta

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Aiming the establishment of simple and accurate readings of citric acid (CA) in complex samples, citrate (CIT) selective electrodes with tubular configuration and polymeric membranes plus a quaternary ammonium ion exchanger were constructed. Several selective membranes were prepared for this purpose, having distinct mediator solvents (with quite different polarities) and, in some cases, p-tert-octylphenol (TOP) as additive. The latter was used regarding a possible increase in selectivity. The general working characteristics of all prepared electrodes were evaluated in a low dispersion flow injection analysis (FIA) manifold by injecting 500 ,l of citrate standard solutions into an ionic strength (IS) adjuster carrier (10 −2 mol l −1 ) flowing at 3 ml min −1 . Good potentiometric response, with an average slope and a repeatability of 61.9 mV per decade and ±0.8%, respectively, resulted from selective membranes comprising additive and bis(2-ethylhexyl)sebacate (bEHS) as mediator solvent. The same membranes conducted as well to the best selectivity characteristics, assessed by the separated solutions method and for several chemical species, such as chloride, nitrate, ascorbate, glucose, fructose and sucrose. Pharmaceutical prepa-rations, soft drinks and beers were analyzed under conditions that enabled simultaneous pH and ionic strength adjustment (pH = 3.2; ionic strength = 10 −2 mol l −1 ), and the attained results agreed well with the used reference method (relative error < 4%). The above experimental conditions promoted a significant increase in sensitivity of the potentiometric response, with a supra-Nernstian slope of 80.2 mV per decade, and allowed the analysis of about 90 samples per hour, with a relative standard deviation <1.0%.

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Section: Introductionmentioning

confidence: 99%

Citrate selective electrodes for the flow injection analysis of soft drinks, beers and pharmaceutical products

Ribeiro¹,

Matos²,

Sales³

et al. 2002

Analytica Chimica Acta

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“…Although relatively slow and expensive in enzyme the approach works well, as a batch method, and is widely used in routine off-line analysis. Since then several other approaches have been proposed; some make use of soluble CL and immobilized MDH with NADH 10 detection, some use CL and oxaloacetate decarboxylase (OACD) in soluble 11 or immobilized 12 form in conjunction with polarography. The direct amperometric determination of citric acid has been proposed 13 in connection with an ascorbate oxidase reactor to eliminate ascorbic acid interference.…”

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confidence: 99%

Bioelectrochemical Determination of Citric Acid in Real Samples Using a Fully Automated Flow Injection Manifold

Tzouwara-Karayanni¹,

Karayannis²,

Prodromidis³

et al. 1997

Analyst

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An enzymic method for the determination of citric acid in fruits, juices and sport drinks is proposed. The method is based on the action of the enzymes citrate lyase, oxaloacetate decarboxylase and pyruvate oxidase, which convert citric acid into H2O2 with the latter being monitored amperometrically with a H2O2 probe. The enzymes pyruvate oxidase and oxaloacetate decarboxylase were immobilized. A multi-membrane system, consisting of a cellulose acetate membrane for the elimination of interferants, an enzymic membrane and a protective polycarbonate membrane were placed on a Pt electrode and used with a fully automated flow injection manifold. Several parameters were optimized, resulting in a readily constructed and reproducible biosensor. Interference from various compounds present in real samples was minimized. Calibration graphs were linear over the range 0.01-0.9 mM pyruvate, 0.015-0.6 mM oxaloacetate and 0.015-0.5 mM citrate. The throughput was 30 samples h-1 with an RSD of 1.0% (n = 8); the mean relative error was 2.4% compared with a standard method. The recovery was 96-104%. A 8-10% loss of the initial activity of the sensor was observed after 100-120 injections.

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New amperometric biosensor for citrate with mercury film electrode

1992

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Differential pulse polarographic determination of citric acid with a soluble enzyme preparation

Cited by 10 publications

References 11 publications

Citrate selective electrodes for the flow injection analysis of soft drinks, beers and pharmaceutical products

Citrate selective electrodes for the flow injection analysis of soft drinks, beers and pharmaceutical products

Bioelectrochemical Determination of Citric Acid in Real Samples Using a Fully Automated Flow Injection Manifold

New amperometric biosensor for citrate with mercury film electrode

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