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Analysis of real samples
The boiler water samples from a power stations contained dispersed colloidal substances and solids, so the key question was
whether the sample preparation procedure (see Section 2) would ensure repeatable results. The relative standard deviation of
the results for these samples was found to be 1.52 % and 1.44 %, respectively. Hence, the repeatability did not significantly
differed from that for homogenous hydrazine solutions.
The elaborated procedure was used for analyses of boiler water samples taken from different locations of a power stations
(Table 3). In all cases, satisfactory agreement was found between the results obtained by the proposed procedure and the
control method. In samples No. 3 and No. 5 (Laboratory A) the chronopotentiometric method provided much lower
hydrazine content than the control method because sample do not stabilizated prior to analysis.
Table 3. Analyses of boiler water samples from a power stations
Sample
Laboratory A
(g L 1 )
Laboratory B
(g L 1 )
Control analysis
(g L 1 )
1 107.6 ± 4.6 99.1 ± 7.2 97.3 ± 7.8
2 84.8 ± 10.8 81.8 ± 9.2 76.1 ± 6.3
3 1.5 ± 0.3 a
3.5 ± 1.3 a 27.5 ± 2.7
4 25.8 ± 3.2 23.9 ± 2.9 28.5 ± 2.8
5 3.0 ± 0.5 a
27.5 ± 1.5 26.5 ± 1.7
Note: a Sample without stabilization prior to analysis.
4. Conclusion
The stripping chronopotentiometric determination of hydrazine provided reliable results for boiler water samples from a
power stations. The sample preparation is simple the prepared sample should be stabilizated prior to the measurement to
obtain values corresponding with the control method. There is no need for a pre-separation step such as in titrimetric and
photometric methods. The automatic on-line matrix exchange in the flow system after deposition minimises possible
interferences from the sample matrix making this technique advantageous over the static batch ones.
The main advantages of the elaborated procedure are the simple sample preparation, no significant interference from sample
matrix, low detection limit, fast and full automatic measurement.
Acknowledgement
The authors appreciate the financial support of the Slovak Grant Agency of Science VEGA (Project No. 1/0500/08).
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Zborník príspevkov
z 18. medzinárodnej vedeckej konferencie
"Analytické metódy a zdravie loveka", ISBN 978-80-969435-7-9
- 87 -
hotel Falkensteiner, Bratislava
11. - 14. 10. 2010