Jiri Barek
Loughborough University
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Featured researches published by Jiri Barek.
Analytica Chimica Acta | 1997
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
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
Jan Fischer; Hana Dejmkova; Jiri Barek
Chemicke Listy | 2007
Ales Danhel; Karolina Pecková; Karel Cizek; Jiri Barek; Jiri Zima; Bogdan Yosypchuk; Tomáš Navrátil
Chemia Analityczna | 2007
Bogdan Yosypchuk; Tomáš Navrátil; Anna N. Lukina; Karolina Pecková; Jiri Barek
Chemicke Listy | 2006
Lucie Vankova; Lucie Maixnerova; Karel Cizek; Jan Fischer; Jiri Barek; Tomáš Navrátil; Bogdan Yosypchuk
Chemicke Listy | 2006
Karolina Pecková; Veronika Mocko; František Opekar; Greg M. Swain; Jiri Zima; Jiri Barek
Chemia Analityczna | 2007
Jiri Zima; Miroslava Cienciala; Jiri Barek; Josino Costa Moreira
Chemia Analityczna | 2009
Tomáš Navrátil; Bogdan Yosypchuk; Jiri Barek
Chemicke Listy | 2002
Josef Cvačka; Greg M. Swain; Jiri Barek; Jiri Zima