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Featured researches published by Jiri Barek.


Analytica Chimica Acta | 1997

Electrochemical investigations of reactive dyes; cathodic stripping voltammetric determination of anthraquinone-based chlorotriazine dyes at a hanging mercury drop electrode

Maria Valnice Boldrin Zanoni; Arnold G. Fogg; Jiri Barek; Jiri Zima

Abstract Two anthraquinone-based chlorotriazine reactive dyes, Procion Blue MX-R and Cibacron Blue 3GA, have been determined at nanomolar levels using cathodic stripping voltammetry. When the differential pulse voltammetric stripping mode is used no peak is obtained for the reduction of the anthraquinone moiety in these dyes, although the signal is present when the linear sweep mode is used. The absence of this peak in the differential pulse mode is believed to occur because, when this group is reduced in the adsorbed state on application of the potential pulse, it is reduced so rapidly that reduction is complete before the current is monitored at the end of the pulse. The differential pulse signal is present for the reduction of the chlorotriazine active groups. The differential pulse peak for the anthraquinone reduction process does appear when boric acid is present in the supporting electrolyte, and it is also present when the chlorotriazine groups are hydrolysed or reacted with other hydroxy compounds. This means that hydrolysis or similar reactions of these dyes can be monitored by observing both the appearance of the anthraquinone peak and the disappearance of the chlorotriazine peak.


Analytica Chimica Acta | 1995

Electrochemical investigations of reactive dyes; polarographic determination of anthraquinone-based chlorotriazine dyes

M.Valnice B. Zanoni; Arnold G. Fogg; Jiri Barek; Jiri Zima

Abstract Direct current and differential pulse polarographic and cyclic voltammetric studies of Procion blue MX-R (PB) and Cibacron blue 3GA (CB) and methods for the determination of PB and CB are reported. For both dyes reduction peaks are observed for the two-electron reversible reduction of the anthraquinone moiety, followed by one (CB) and two (PB) reduction processes associated with the reduction of the mono- and dichlorotriazine groups, respectively. These latter processes appear to involve the reductive elimination of the chlorine atoms: only the anthraquinone reduction process is observed when the dyes are hydrolysed. In alkaline solution the reduction processes are complicated by adsorption and kinetic effects. For this reason determination of the dyes is best carried out in acidic solution, but determination is also possible in alkaline solution, which would be more convenient for monitoring the dyes during dyeing and other nucleophilic reactions.


Current Organic Chemistry | 2011

Electrochemistry of Pesticides and its Analytical Applications

Jan Fischer; Hana Dejmkova; Jiri Barek


Chemicke Listy | 2007

Voltametrické stanovení genotoxických dinitronaftalenu pomocí rtutovým meniskem modifikované stribrné pevné amalgámové elektrody

Ales Danhel; Karolina Pecková; Karel Cizek; Jiri Barek; Jiri Zima; Bogdan Yosypchuk; Tomáš Navrátil


Chemia Analityczna | 2007

Solid amalgam composite electrode as a new sensor for the determination of biologically active compounds

Bogdan Yosypchuk; Tomáš Navrátil; Anna N. Lukina; Karolina Pecková; Jiri Barek


Chemicke Listy | 2006

Voltametrické stanovení submikromolárních koncen trací 3-nitrofluoranthenu a pendimethalinu na stribrné pevné amalgamové elektrodé

Lucie Vankova; Lucie Maixnerova; Karel Cizek; Jan Fischer; Jiri Barek; Tomáš Navrátil; Bogdan Yosypchuk


Chemicke Listy | 2006

Miniaturizované ampero-metrické detektory pro HPLC a kapilární zónovou elektro-forézu

Karolina Pecková; Veronika Mocko; František Opekar; Greg M. Swain; Jiri Zima; Jiri Barek


Chemia Analityczna | 2007

Determination of thymol using HPLC-ED with glassy carbon paste electrode

Jiri Zima; Miroslava Cienciala; Jiri Barek; Josino Costa Moreira


Chemia Analityczna | 2009

A multisensor for electrochemical sequential autonomous automatic measurements

Tomáš Navrátil; Bogdan Yosypchuk; Jiri Barek


Chemicke Listy | 2002

Stanovení aminonaftalen˚U a aminobifenyl˚U kapalinovou chromatografií s amperometrickou detekcí na diamantové filmové elektrodě

Josef Cvačka; Greg M. Swain; Jiri Barek; Jiri Zima

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Jiri Zima

Loughborough University

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Jan Fischer

Charles University in Prague

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Bogdan Yosypchuk

Academy of Sciences of the Czech Republic

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Jiri Zima

Loughborough University

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Tomáš Navrátil

Academy of Sciences of the Czech Republic

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Joseph Wang

University of California

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Karel Cizek

Charles University in Prague

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Karolina Pecková

Charles University in Prague

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