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Determination of Ag+ and Cu2+ ions in mixture samples obtained in the microwave assisted polyol process by differential pulse anodic stripping voltammetry (DPASV) method

100%

Markowski P., Dzido G., Baranowska I., Jarzębski A. B.

Open Chemistry

2015

vol. 13

issue 1

A simple and selective differential pulse anodic stripping voltammetry (DPASV) method for the determination of Ag+ and Cu2+ ions in mixture samples obtained in the microwave assisted polyol process was developed and validated. Analytical methods for the preparation of the reaction mixture for voltammetric analysis (dilute samples in the supporting electrolyte) were worked out and optimized. All measurements were conducted in three-electrode cell system equipped with glassy carbon electrode (GCE) as a working electrode, silver/silver chloride (Ag|AgCl|KCl(sat.)) as a reference and platinum wire as a auxiliary electrode. The optimal conditions for quantitative determination were obtained in an mixture Britton–Robinson buffer at pH 4.1 / ethylene glycol (100/1; v/v). The calibration curves of analysed compounds are linear within the range of concentration: 0.032 − 0.420 μg mL-1 and 0.075 − 0.960 μg mL-1 for Ag+ and Cu2+, respectively. Good linear behaviour over the investigated concentration ranges were observed with the values of r2 higher than 0.996 for the silver and cooper ions. The accuracy of analytical determinations ranged from 0.4 to 3.6%. The levels of analysed ions in the reaction mixture can be successfully determined using this developed method with no matrix effect.

Laccase Immobilisation on Mesostructured Silicas

100%

Bryjak J., Szymańska K., Jarzębski A. B.

Chemical and Process Engineering

2012

vol. 33

issue 4

611-620

Extracellular laccase produced by the wood-rotting fungus Cerrena unicolor was immobilised covalently on the mesostructured siliceous foam (MCF) and three hexagonally ordered mesoporous silicas (SBA-15) with different pore sizes. The enzyme was attached covalently via glutaraldehyde (GLA) or by simple adsorption and additionally crosslinked with GLA. The experiments indicated that laccase bound by covalent attachment remains very active and stable. The best biocatalysts were MCF and SBA-15 with Si-F moieties on their surface. Thermal inactivation of immobilised and native laccase at 80°C showed a biphasic-type activity decay, that could be modelled with 3- parameter isoenzyme model. It appeared that immobilisation did not significantly change the mechanism of activity loss but stabilised a fraction of a stable isoform. Examination of time needed for 90% initial activity loss revealed that immobilisation prolonged that time from 8 min (native enzyme) up to 155 min (SBA-15SF).

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1 Chemical and Process Engineering

1 Open Chemistry

1 2014

1 2012

2 Jarzębski A. B.

1 Baranowska I.

1 Bryjak J.

1 Dzido G.

1 Markowski P.

1 Szymańska K.

Search results

Determination of Ag+ and Cu2+ ions in mixture samples obtained in the microwave assisted polyol process by differential pulse anodic stripping voltammetry (DPASV) method

Laccase Immobilisation on Mesostructured Silicas