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dc.contributor.authorApak, Resat
dc.contributor.authorOzyurek, Mustafa
dc.contributor.authorGuclu, Kubilay
dc.contributor.authorBektasoglu, Burcu
dc.date.accessioned2021-03-05T18:16:37Z
dc.date.available2021-03-05T18:16:37Z
dc.date.issued2007
dc.identifier.citationOzyurek M., Guclu K., Bektasoglu B., Apak R., "Spectrophotometric determination of ascorbic acid by the modified CUPRAC method with extractive separation of flavonoids-La(III) complexes", ANALYTICA CHIMICA ACTA, cilt.588, ss.88-95, 2007
dc.identifier.issn0003-2670
dc.identifier.otherav_c9862aaf-7470-4aac-b72d-bf5f039f7392
dc.identifier.othervv_1032021
dc.identifier.urihttp://hdl.handle.net/20.500.12627/133536
dc.identifier.urihttps://doi.org/10.1016/j.aca.2007.01.078
dc.description.abstractThe proposed method for ascorbic acid: AA (Vitamin Q determination is based on the oxidation of AA to dehydroascorbic acid with the CUPRAC reagent of total antioxidant capacity assay, i.e., Cu(II)-neocuproine (Nc), in ammonium acetate-containing medium at pH 7, where the absorbance of the formed bis(Nc)-copper(I) chelate is measured at 450 nm. The flavonoids (essentially flavones and flavonols) normally interfering with the CUPRAC procedure were separated with preliminary extraction as their La(III) chelates into ethylacetate (EtAc). The Cu(I)-Nc chelate responsible for color development was formed immediately with AA oxidation. Beer's law was obeyed between 8.0 x 10(-6) and 8.0 x 10(-5) M concentration range, with the equation of the linear calibration curve: A(450nm) = 1.60 x 10(4)C (mol dm(-3)) -0.0596. The relative standard deviation (R.S.D.) in the analysis of N=45 synthetic mixtures containing 1.25 x 10(-2) mM AA with flavonoids was 5.3%. The Cu(II)-Nc reagent is a lower redox-potential and therefore more selective oxidant than the Fe(III)-1,10-phenanthroline reagent conventionally used for the same assay. This feature makes the proposed method superior for real samples such as fruit juices containing weak reductants such as citrate, oxalate and tartarate that may otherwise produce positive errors in the Fe(III)-phen method when equilibrium is achieved. The developed method was applied to some commercial fruit juices and pharmaceutical preparations containing Vitamin C + bioflavonoids. The findings of the developed method for fruit juices and pharmaceuticals were statistically alike with those of HPLC. The proposed spectrophotometric method was practical, low-cost, rapid, and could reliably assay AA in the presence of flavonoids without enzymatic procedures open to interferences by enzyme inhibitors. (c) 2007 Elsevier B.V. All rights reserved.
dc.language.isoeng
dc.subjectTemel Bilimler (SCI)
dc.subjectTemel Bilimler
dc.subjectKİMYA, ANALİTİK
dc.subjectKimya
dc.subjectAnalitik Kimya
dc.titleSpectrophotometric determination of ascorbic acid by the modified CUPRAC method with extractive separation of flavonoids-La(III) complexes
dc.typeMakale
dc.relation.journalANALYTICA CHIMICA ACTA
dc.contributor.department, ,
dc.identifier.volume588
dc.identifier.issue1
dc.identifier.startpage88
dc.identifier.endpage95
dc.contributor.firstauthorID52975


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