Zborník príspevkov z vedeckej konferencie - Department of ...

2. Experimental
Instrumentation
Flow-through chronopotentiometric measurements were carried out by an electrochemical analyser EcaFlow model GLP 150
(Istran Ltd., Slovakia) equipped with two solenoid inert valves, a peristaltic pump, 1 mm inner diameter PTFE tubing and a
microprocessor controlled potentiostat/galvanostat. The block diagram of the system was reported elsewhere [17]. The
signals were recorded and evaluated by the memory-mapping technique [18, 19]. The measurement consists of two main
steps: (i) the background signal is measured first by means of a blank sample, (ii) followed by the sample or standard solution
giving the signal of the sample or standard. The sample or standard is preconcentrated and the cell is rinsed with the carrier
electrolyte into which the deposit is stripped. The cell is then rinsed again to remove the stripped hydrazine ions enabling the
next run. The background signal is then subtracted from the signal of the standard or sample yielding the corresponding
background corrected net signal. A compact flow-through electrochemical cell of type 353 with Pt auxiliary and Ag/AgCl
reference electrodes was used (Istran Ltd., Slovakia). The working electrode was a reticulated vitreous carbon plug of 100 ppi
(pores per inch) porosity (Electrosynthesis Co. Inc., Lancaster, New York, USA) of 10 mm and 4 mm in diameter and length,
respectively. We are used two type of the electrodes: microporous electrode E-53C which is characterized by a large active
surface (up to 25 cm 2 ) and low internal volume (only 20 l) and macroporous electrode E-104C which is also characterized
by active surface (10 cm 2 ) and large volume (300 l).
The operation parameters are listed in Table 1 for microporous electrode and in Table 2 for macroporous electrode,
respectively. All potentials are expressed versus the silver/silver chloride reference electrode built in the cell.
Table 1. Operation parameters of the flow-through electrochemical analyser for microporous electrode
Parameter Dimension Value
Deposition potential mV 200
Quiescence potential I mV 200
Quiescence time I s 5
Quiescence potential II mV -200
Quiescence time II s 5
Terminal potential mV 1000
Regeneration potential mV 0
Standby potential mV 0
Stripping current A 200
Sample volume mL 4
Blank volume mL 4
Rinsing volume mL 4
Flow rate mL/min 6
Table 2. Operation parameters of the flow-through electrochemical analyser for macroporous electrode
Parameter Dimension Value
Deposition potential mV 200
Quiescence potential I mV 200
Quiescence time I s 5
Quiescence potential II mV -200
Quiescence time II s 5
Terminal potential mV 800
Regeneration potential mV 0
Standby potential mV 0
Stripping current A 10
Sample volume mL 4
Blank volume mL 4
Rinsing volume mL 4
Flow rate mL/min 6
Zborník príspevkov
z 18. medzinárodnej vedeckej konferencie
"Analytické metódy a zdravie loveka", ISBN 978-80-969435-7-9
- 85 -
hotel Falkensteiner, Bratislava
11. - 14. 10. 2010