ELECTROCHEMICAL DETERMINATION OF HEAVY METALS IN
RAINWATER
Petr MAJZLÍK1, David HYNEK1, Rene KIZEK1,2*
1
Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in
Brno, Zemedelska 1, 613 00 Brno, Czech Republic
2 Central European Institute of Technology, Brno University of Technology, Technicka
3058/10, 616 00 Brno, Czech Republic
*kizek@sci.muni.cz
Abstract
Electrochemical determination of heavy metals in rain water is the aim of this paper.
Determination of heavy metals in rainwater from weather-station Bořitov in course of one
year was carried out. For electrochemical determination measuring system Metrohm
(Autosampler 813 Compact and measuring unit VA Computrace 797) was employed.
1. INTRODUCTION
Electrochemical determination of heavy metals in rain water is simple, practic and useful way
how to check the amount of heavy metals in environment [1]. Zinc, cadmium, lead and copper
belong to the group of heavy metals [2]. There are two insights into pollution of living
environment by heavy metals [3]. First represents occurrence of these metals in rocks, from
which can be gradually released and entry the plants, respectively food chain. Second
possibility of occurrence of heavy metals in living environment represents human itself due to
anthropogenic activity (mining and processing of ore, chemical industry). Heavy metals
represent significant problem, especially because of their toxicity, which may cause acute as
well as chronic intoxication and lead to origination of malignant tumour disease [4 - 6]. Due
to these facts, improving of methods of their qualification and quantification using various
measuring procedures is very advisable.
2. MATERIAL AND METHODS
Electrochemical determination
Measuring system Metrohm was employed for the determination of
heavy metals –
Autosampler 813 Compact and measuring unit VA Computrace 797. Samples were prepared
in this manner: 15μl of sample were mixed with 985μl of acetic buffer (pH = 5). Diferential
pulse voltametry was used for the measurement with these parameters: potencial of deposition
-1,3V, time of deposition 240s, range of potencial from -1,3V to 0,15V, pulse amplitude
0,025V, pulse time 0,04s, unit step 0,005035V, time of unit step 0,3s. A standard cell with
three electrodes was used for the measurment. A hanging mercury drop electrode (HMDE)
with a drop area of 0.4 mm2 was employed as the working electrode. An Ag/AgCl/3M KCl
electrode served as the reference electrode. Pt electrode was used as the auxiliary electrode.
3. RESULTS AND DISCUSSION
Measurement of heavy metals by DPV technique has been described many times over in
literature; therefore, it is not necessary to represent accomplishments and negatives of this
technique. Main aim of our work consisted in proposing and realization of automated
measuring procedure for analysis of defined small volume of sample for determination of
above mentioned heavy metals in rainwater. Preparation of sample proceeded in accordance
with following procedure: volume of 15μl of sample for measurement of heavy metals (Zn,
Cd, and Cu) was placed into Eppendorf micro test tube together with 985μl of acetate buffer
(pH 5.00). Samples were subsequently placed into Autosampler 813; in enclosed software, list
of measured samples was created.
Dependence of buffer pH and concentration of heavy metals illustrates Fig. 1. It is obvious
that the best detection of heavy metals is by pH 5.00. That is the reason for use of acetic
buffer pH 5.00 for other measurements.
Figure 1.: Dependence of buffer pH and system response
Rainwater samples were measured for present of heavy metals. Furthermore conductivity and
pH were measured. Average characteristic values for each season in one year are presented in
Table 1. Concentration of pollutants which are presented in table is increasing in summer
months. Opposite in winter the concentration of pollutants is higher. Probably it is due to
human activity, especially heating and pollutants emitted into air). Dependence of pH in one
year is increasing from spring to winter as well as conductivity.
Table 1: Comparison of various characterictic values in course of one year.
pH
conductivity
(µS/cm)
conc. Zn
(µM)
conc. Cd
(µM)
conc. Pb
(µM)
conc. Cu
(µM)
1.
spring
(6,53)
spring
(56,12)
spring
(28,05)
spring
(0,54)
spring
(1,29)
spring
(21,58)
2.
summer
(6,37)
summer
(63,38)
summer
(29,32)
summer
(0,12)
summer
(1,44)
summer
(19,91)
3.
autumn
(6,90)
autumn
(71,74)
autumn
(90,41)
autumn
(5,66)
autumn
(4,55)
autumn
(37,27)
4.
winter
(7,15)
winter
(88,47)
winter
(98,80)
winter
(6.00)
winter
(7,06)
winter
(51,06)
4. CONCLUSION
Monitoring of amount of heavy metals in rainwater is presented in this paper. Electrochemical
detection of heavy metals represents analytical method with good reproducibility, effortless
service and relatively rapid determination. It seems to be good analytical tool for periodic
determination of heavy metals in rainwater. Monitoring of pollutants in rainwater is very
useful tool for environment control.
5. ACKNOWLEDGEMENT
The work has been supported by NANIMEL GA ČR 102/08/1546.
6. REFERENCES
[1] Vacek J, Petrek J, Kizek R, et all.: Bioelectrochemistry, 63 (2004), 1-2, 347-351
[1] Strouhal M, Kizek R, Vacek J, et all.: Bioelectrochemistry, 60 (2003), 1-2, 29-36
[2] Adam V, Petrlova J, Potesil D, et all.: Electroanalysis, 17 (2005), 18, 1649-1657
[3] Kovarova J, Kizek R, Adam V, et all.: Sensors, 9 (2009), 6, 4789-4803
[4] Adam V, Sileny J, Hubalek J, et all.: Toxicology Letters, 180 (2008), Suppl.1, S227-S228
[5] Adam V, Fabrik I, Kohoutkova V, et all.: International Journal of Electrochemical
Science, 5 (2010), 429-447
[6] Krystofova O, Trnkova L, Adam V, et all.: Sensors, 10, 6, 5308-5328