Bachelor Thesis VALIDATION OF ELECTROANALYTICAL METHOD WITH ANTIMONY ELECTRODE FOR TRACE METAL ANALYSIS September, 2017 Aljaž Ramot
Bachelor Thesis
VALIDATION OF ELECTROANALYTICAL METHOD WITH ANTIMONY ELECTRODE FOR TRACE METAL
ANALYSIS
September, 2017 Aljaž Ramot
Aljaž Ramot
Validation of electroanalytical method with antimony electrode for trace metal analysis
Bachelor Thesis
Maribor, 2017
Validacija elektroanalizne metode z antimonovo
elektrodo za analizo težkih kovin v sledovih
Diplomsko delo visokošolskega strokovnega študijskega programa I.
stopnje
Študent: Aljaž Ramot
Študijski program: visokošolski strokovni študijski program I. stopnje
Kemijska tehnologija
Predvideni strokovni naslov: diplomirani inženir kemijske tehnologije (VS)
Mentor: doc. dr. Matjaž Finšgar
Komentor: asist. Barbara Petovar, mag. kem.
Maribor, 2017
Validation of electroanalytical method with antimony electrode for trace metal analysis
I
Table of Contents
.......................................................................................................................................... IV Table of Contents ................................................................................................................. I Izjava.................................................................................................................................. II
Acknowledgments ............................................................................................................ III Validacija elektroanalizne metode z antimonovo elektrodo za analizo težkih kovin v
sledovih ................................................................................................................................... IV Povzetek ............................................................................................................................ IV Validation of electroanalytical method with antimony electrode for trace metal analysis V
Abstract .............................................................................................................................. V List of Tables .................................................................................................................... VI List of Figures ................................................................................................................. VII
List of Symbols and Abbreviations .................................................................................. IX 1. Introduction and identifying the problem ................................................................ 10
1.1. Identifying the problem .................................................................................... 10
1.2. Heavy metals .................................................................................................... 10 1.3. The effect of heavy metals on organisms and on the environment .................. 10 1.4. Validation of electroanalytical method ............................................................. 11
1.4.1. Limit of detection (LOD) and limit of quantitation (LOQ) ....................... 11 1.4.2. Linearity and calibration curve.................................................................. 11
1.4.3. Outliers per Dixon’s and Grubbs’ tests ..................................................... 11
1.4.4. RSD (relative standard deviation) ............................................................. 12
1.5. Scientific background ....................................................................................... 12 1.6. The Hypothesis, purpose and goal of the thesis ............................................... 13
2. Analytical method .................................................................................................... 14 2.1. Square-wave anodic stripping voltammetry (SWASV) ................................... 14
3. Experimental ............................................................................................................ 16
3.1. Cyclic voltammetry (CV) ................................................................................. 17
3.2. Materials ........................................................................................................... 19 4. Results and discussion ............................................................................................. 20
4.1. LOD and LOQ analysis .................................................................................... 20 4.2. Linearity ............................................................................................................ 22 4.3. Accuracy ........................................................................................................... 26
5. Conclusion ............................................................................................................... 33 6. References ................................................................................................................ 34
7. Življenjepis (CV) ..................................................................................................... 35
Validation of electroanalytical method with antimony electrode for trace metal analysis
II
Izjava
Izjavljam, da sem diplomsko delo izdelal/a sam/a, prispevki drugih so posebej
označeni. Pregledal/a sem literaturo s področja diplomskega dela po naslednjih geslih:
Vir: Sciencedirect (http://www.sciencedirect.com/)
Gesla: Število
referenc
Anodic stripping voltammetry 35
Square-wave voltammetry 17
Heavy metals 48
Antimony film electrode 18
Vir: Google Books (http://books.google.com/)
Gesla: Število
referenc
Cyclic voltammetry 30
Antimony IN electroanalysis 25
Skupno število pregledanih člankov: 24
Skupno število pregledanih knjig: 6
Maribor, September 2017 Aljaž Ramot
Validation of electroanalytical method with antimony electrode for trace metal analysis
III
Acknowledgments
I would like to thank my thesis advisor, doc. dr. Matjaž
Finšgar and co-advisor, asist. Barbara Petovar, mag. kem. The
door to their offices were always open whenever I had questions
about my writing. Special thanks go to my friend Vid Baklan for
proofreading this thesis. I would also like to thank my family
members, for their support and encouragement throughout my
life.
Validation of electroanalytical method with antimony electrode for trace metal analysis
IV
Validacija elektroanalizne metode z antimonovo elektrodo za
analizo težkih kovin v sledovih
Povzetek
Namen diplomskega dela je validacija elektroanalizne metode z antimonovo elektrodo za
analizo težkih kovin v sledovih. Validacija se je pričela z določevanjem meje zaznavnosti
(LOD) in meje kvantifikacije (LOQ), nadaljevala z določanjem linearnosti in končala z
določanjem točnosti in natančnosti. Analiza težkih kovin je bila izvedena s square-wave
anodno striping voltametrijo (SWASV), za testiranje reverzibilnosti sistema
[Fe(CN)6]-3/[Fe(CN)6]
-4 pa smo uporabili metodo ciklične voltametrije (CV). Vse analize so
bile izvedene v 0,01 M raztopini HCl.
Meje LOD in LOQ ni mogoče določiti z dovolj veliko gotovostjo, saj ima metoda tako
nizko LOD, da je bila kontaminacija s težkimi kovinami, tudi v ultra čisti kislini, prevelika.
Metoda ima linearen odziv pri potencialih depozicije -1,2 V, -1,1 V in -1,0 V vs. Ag/AgCl za
Pb(II) in Cd(II) v območju od 14,6 µg L-1 do 100,0 µg L-1. Točnost metode se je preverila za
koncentracije 15 µg L-1, 25 µg L-1, 30 µg L-1, 40 µg L-1 pri vseh treh potencialih depozicije.
Ugotovljeno je bilo, da je metoda najbolj točna in natančna pri potencialu depozicije -1,1 V
vs. Ag/AgCl.
Ključne besede: Analiza težkih kovin, analitika sledov, antimonova elektroda, SWASV,
voltametrija.
UDK: 543.55:549.25(043.2)
Validation of electroanalytical method with antimony electrode for trace metal analysis
V
Validation of electroanalytical method with antimony electrode for
trace metal analysis
Abstract
The purpose of this thesis is to validate the electroanalytical method with an antimony
electrode for trace metal analysis. The validation began with the determination of the limit of
detection (LOD) and the limit of quantification (LOQ), proceeded with determining the
method’s linearity and concluded with determination of accuracy and precision. The trace
metal analysis was conducted via square-wave anodic stripping voltammetry (SWASV).
Cyclic voltammetry (CV) was used to test the reversibility of the [Fe(CN)6]-3/[Fe(CN)6]
-4
system. All the analyses were conducted in a 0.01 M HCl solution.
The LOD and LOQ were not possible to report with certainty, since the method has such
a low LOD that the contamination with heavy metals, even in ultrapure acid, was too high.
The method had a linear response at deposition potentials of -1.2 V, -1.1 V and -1.0 V vs.
Ag/AgCl for Pb(II) and Cd(II) from 14.6 µg L-1 to 100.0 µg L-1. The precision of the method
was tested at 15 µg L-1, 25 µg L-1, 30 µg L-1 and 40 µg L-1 for all three deposition potentials.
The results have shown that the method is the most accurate and precise at a deposition
potential of -1.1 V vs. Ag/AgCl.
Key words: heavy metal analysis, trace analysis, antimony electrode, SWASV, voltammetry
UDK: 543.55:549.25(043.2)
Validation of electroanalytical method with antimony electrode for trace metal analysis
VI
List of Tables
Table 3-1: Results were similar to the proposed guidelines mentioned above ....................... 17
Table 4-1: Linearity regression analysis of Cd(II) plot at a -1.2 V deposition potential for all
three curves. ............................................................................................................................ 23
Table 4-2: Linearity regression analysis of Cd(II) plot at a -1.1 V deposition potential for all
three curves. ............................................................................................................................ 24
Table 4-3: Linearity regression analysis of Cd(II) plot at a -1.0 V deposition potential for all
three curves. ............................................................................................................................ 24
Table 4-4: Linearity regression analysis of Pb(II) plot at a -1.2 V deposition potential for both
curves. ..................................................................................................................................... 25
Table 4-5: Linearity regression analysis of Pb(II) plot at a -1.1 V deposition potential for both
curves. ..................................................................................................................................... 25
Table 4-6: Linearity regression analysis of Pb(II) plot at a -1.0 V deposition potential for both
curves. ..................................................................................................................................... 26
Table 4-7: Recovery determined for concentration at 15.0 µg L-1 ........................................ 29
Table 4-8: Recovery determined for concentration at 25.0 µg L-1 ......................................... 30
Table 4-9: Recovery determined for concentration at 30.0 µg L-1 ......................................... 30
Table 4-10: Recovery determined for concentration at 40.0 µg L-1 ....................................... 31
Validation of electroanalytical method with antimony electrode for trace metal analysis
VII
List of Figures
Figure 2-1: An example of anodic stripping voltammogram ................................................. 14
Figure 2-2: (A) potential waveform, (B) one potential cycle, (C) voltammogram in SWV. The
response consists out of a forward (anodic, ψf), backward (cathodic, ψb) and net (ψnet)
component [15]. ...................................................................................................................... 15
Figure 3-1: Polishing cloth and the aluminium oxide paste ................................................... 16
Figure 3-2: The linear plot of the peak current vs. square root of the scan rate, which indicates
that the reaction is controlled by diffusion. ............................................................................ 18
Figure 3-3: Cyclic voltammogram of potassium ferricyanide, at different scan rates given in
Table 3-1, starting with 10 mV/s and increasing to 200 mV/s. .............................................. 18
Figure 4-1: The reduction peaks for Cd(II) (at -0.75 V) and Pb(II) (at -0.36 V)in the blank
0.01 M HCl solution using different deposition potentials: -1.0 V (blue curve), -1.1 V (red
curve) and -1.2 V (green curve). ............................................................................................. 20
Figure 4-2: The reduction peaks for Cd(II) (at -0.75 V) and Pb(II) (at -0.33 V) in the blank
solution in ultrapure HCl acid using different deposition potentials: : -1.0 V (blue
curve), -1.1 V (red curve) and -1.2 V (green curve). .............................................................. 21
Figure 4-3: Concentration range for Pb(II) from 1.0 µg L-1 to 106.3 µg L-1. Points represent
values at different deposition potentials, blue at -1.2 V, orange at -1.1 V and gray at -1.0 V.
................................................................................................................................................ 22
Figure 4-4: Concentration range for Cd(II) from 1.0 µg L-1 to 106.3 µg L-1. Points represent
values at different deposition potentials, blue at -1.2 V, orange at -1.1 V and gray at -1.0 V.
................................................................................................................................................ 22
Figure 4-5: Three replicates for the resulting calibration plot linear for Cd(II) response at
a -1.2 V deposition potential. Linearity regression analysis parameters for all three replicates
are given in Table 4-1. ............................................................................................................ 23
Figure 4-6: Three replicates for the resulting calibration plot linear for Cd(II) response at
a -1.1 V deposition potential. Linearity regression analysis parameters for all three replicates
are given in Table 4-2. ............................................................................................................ 23
Figure 4-7: Three replicates for the resulting calibration plot linear for Cd(II) response at
a -1.0 V deposition potential. Linearity regression analysis parameters for all three replicates
are given in Table 4-3. ............................................................................................................ 24
Figure 4-8: Two replicates for the resulting calibration plot linear for Pb(II) response at
a -1.2 V deposition potential. Linearity regression analysis parameters for both replicates are
given in Table 4-4. .................................................................................................................. 25
Figure 4-9: Two replicates for the resulting calibration plot linear for Pb(II) response at
a -1.1 V deposition potential. Linearity regression analysis parameters for both replicates are
given in Table 4-5. .................................................................................................................. 25
Figure 4-10: Two replicates for the resulting calibration plot linear for Pb(II) response at
a -1.1 V deposition potential. Linearity regression analysis parameters for both replicates are
given in Table 4-6. .................................................................................................................. 26
Figure 4-11: Calibration curve for Cd(II) at a deposition potential of -1.2 V. ....................... 27
Figure 4-12: Calibration curve for Cd(II) at a deposition potential of -1.1 V. ....................... 27
Figure 4-13: Calibration curve for Cd(II) at a deposition potential of -1.0 V. ....................... 28
Figure 4-14: Calibration curve for Pb(II) at a deposition potential of -1.2 V. ....................... 28
Validation of electroanalytical method with antimony electrode for trace metal analysis
VIII
Figure 4-15: Calibration curve for Pb(II) at a deposition potential of -1.1 V. ....................... 28
Figure 4-16: Calibration curve for Pb(II) at a deposition potential of -1.0 V. ........................ 29
Validation of electroanalytical method with antimony electrode for trace metal analysis
IX
List of Symbols and Abbreviations
Symbols
Ipa Anodic current peak [A]
Ipc Cathodic current peak [A]
Ip Peak current [A]
Epa Anodic potential peak [V]
Epc Cathodic potential peak [V]
Ep Peak potential [V]
Esw Square wave amplitude [V]
Greek Symbols
Ψf anodic component
Ψb cathodic component
Ψnet net component
mass concentration [g/L]
υ scan rate [V/s]
Abbreviations
APL Acute Promyelocytic Leukaemia
ASV Anodic Stripping Voltammetry
SbFE Antimony Film Electrode
SbFGCE Antimony Film Modified Glassy Carbon Electrode
CV Cyclic Voltammetry
GCE Glassy Carbon Electrode
LOD Limit of Detection
LOQ Limit of Quantification
RSD Relative Standard Deviation
SWASV Square-wave Anodic Stripping Voltammetry
SWV Square-wave Voltammetry
SHE Standard Hydrogen Electrode
SCP Stripping Chronopotentiometry
Validation of electroanalytical method with antimony electrode for trace metal analysis
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1. Introduction and identifying the problem
1.1. Identifying the problem Heavy metals are naturally occurring materials that can be found in the Earth’s crust [1].
They are known to be toxic for humans and other organisms even in small quantities, which is
why constant supervision of the amount of heavy metals in nature is of paramount importance.
With supervision, possible contaminations can be discovered faster, thus decreasing the impact
of heavy metals on the environment [2].
In the analysis of heavy metals in aquatic environments, the conventional mercury electrode
was mostly used due to its unique attributes [3]. Its 60-year dominance seems to be coming to
an end, however, since it is being increasingly replaced by newer, environmentally-friendlier,
electrodes [4]. The replacement of Hg-electrodes is further supported by the European Union,
which banned the authorisation of mercury from 2015 onwards with a directive
(European Directive 2008/105/EC) [3]. The development of new electroanalytical methods is
inevitable despite already familiar alternatives, such as the bismuth electrode, since the entire
field of stripping analysis is moving towards using mercury-free electrodes, which means that
development in this area is of vital importance [4].
1.2. Heavy metals There are several definitions for the term ‘heavy metals’, but it is agreed that elements
classified as heavy metals have a relatively high density when compared to water (at least five
times as high) [5]. They also have a similar configuration of electrons in their outer orbitals [2].
Over 50 elements can be classified as heavy metals, including some metalloids, lanthanides and
actinides.
1.3. The effect of heavy metals on organisms and on the environment
The occurrence of heavy metals is a completely natural phenomenon, which occurs for
example during volcano eruptions. However, there is a growing concern regarding the effects
of heavy metals on health in recent years, since the environment is becoming more and more
artificially contaminated with heavy metals [5]. Several large industries have contributed to the
rise in concentration of heavy metals in our ecosystem over the last few decades and human
exposure to these metals has increased due to new developments in the fields of agriculture,
industry and technology [2, 5].
The issue with heavy metals is that they cannot be degraded or destroyed, while being
bioaccumulative, meaning that their quantity in an organism increases over time, even though
the organism itself does not change. As a result, heavy metals are accumulating at a faster rate
than the organism can extract them [1]. Most heavy metals are classified as harmful chemicals,
but some can disturb endocrine glands or can even be carcinogens [2]. Their toxicity and their
effect on a system depend on several factors, such as the amount consumed, the level of
exposure and the genes, age and gender of individual exposed subjects [5]. It is important to
recognise that heavy metals enter our body every day via food, water and air, but in small,
harmless quantities. Smaller amounts of metals, such as copper, zinc and selenium, are even
essential to the human metabolism [1]. It is further worth noting that certain metals with no
known biologic function in the body can have positive impacts. An example of this is arsenic
trioxide being used to treat acute promyelocytic leukaemia (APL) [6].
Validation of electroanalytical method with antimony electrode for trace metal analysis
11
1.4. Validation of electroanalytical method
1.4.1. Limit of detection (LOD) and limit of quantitation (LOQ)
LOD and LOQ can be defined in many ways. The definition employed herein was based on
the signal to noise ratio in line with the ICH (International Conference on Harmonization of
Technical Requirements for Registration of Pharmaceuticals for Human Use) standards.
- LOD: The lowest amount of the analyte still detected in the sample, but whose
quantitative value cannot be determined with certainty. The LOD is determined when
the signal to noise ratio (S/N) is greater than or equal to 3 [7].
- LOQ: The lowest amount of the analyte still quantified in the sample with a satisfactory
accuracy. The LOQ is determined when the signal to noise ratio is greater than or equal
to 10 [7].
1.4.2. Linearity and calibration curve
The linearity of the method reveals if the measured signal is linearly proportional to the
concentration in a certain range. To determine the linearity, measurements of at least six
concentrations in the defined concentration range need to be carried out [8].
1.4.3. Outliers per Dixon’s and Grubbs’ tests
Data is analysed for outliers when there is a suspicion of errors during the measurements
and that certain measurements need to be excluded. The purpose of identifying outliers is to
assess the measuring process, which is why certain rules need to be followed during this. There
can be several causes for outliers to occur:
- experimental errors,
- errors during measuring,
- outliers can be completely random.
Several standardised tests are used to test outliers [9]. Among the most popular are Dixon’s
test, established by the international standard (ISO 5725-1986(E)), and the newer Grubbs’ test,
established by the international standard (ISO 5725-2:1994(E)). The latter also permits the use
of Dixon’s test [10].
Before the testing can start, all the data is sorted from the smallest to the largest in
accordance to the attribute that is important to us. The null hypothesis H0 in both tests states:
the tested value is an outlier [10].
Dixon’s test:
Another factor that needs to be considered is whether we are testing the maximal or
minimal value for outliers:
Qfor 3-7 objects=𝑥2−𝑥1
𝑥𝑚𝑎𝑥−𝑥1 or Qfor 3-7 objects=
𝑥𝑚𝑎𝑥−𝑥𝑚𝑎𝑥−1
𝑥𝑚𝑎𝑥−𝑥1 (1.1)
Where:
Q Critical value of Dixon’s outlier Test
xmax Outlier with the highest value
x1 Outlier with the lowest value
Validation of electroanalytical method with antimony electrode for trace metal analysis
12
The null hypothesis is confirmed, if Qmeasurement > Qtable, meaning the measurement is an
outlier [10].
Grubbs’ test:
G1one outlier=
−𝑥𝑚𝑖𝑛
𝑠 or G1
one outlier=𝑥𝑚𝑎𝑥−
𝑠 (1.2)
Where:
G Critical value of Grubbs’ outlier test
xmax Outlier with the highest value
xmin Outlier with the lowest value
s Standard deviation
Mean value
The first equation is used when testing the minimal value, and the second equation for testing
the maximal value.
A measurement is an outlier, if G1measurement > Gtable [10].
1.4.4. RSD (relative standard deviation)
RSD (relative standard deviation) reveals, if a “regular” standard deviation is big or small
in comparison to average measurements. A small RSD means that the data is closely gathered
around the average. In contrast, if the RSD is big, the data is more scattered out [11].
𝑅𝑆𝐷 =𝑠
(1.3)
1.5. Scientific background There is only a limited number of scientific articles discussing the topic of the efficiency
and validation of antimony electrodes. Those written mainly include the validation process,
reactions and final efficiency of the electrode. The studies conducted so far have shown that
work with antimony electrodes has provided promising results.
Jovanovski et al. [4] studied an antimony electrode which was, contrary to our experiment,
prepared ex situ for anodic stripping voltammetry (ASV) and adsorptive stripping
voltammetry (AdSV) . Their results have revealed good linearity of the electrode for Cd(II) and
Pb(II) ions in a nondeaerated solution of 0.01 M HCl in the examined concentration range from
25 µg L-1 to 80 µg L-1. They have also revealed the LOD for Cd(II) at 1.1 µg L-1 and 0.3 µg L-1
for Pb(II). The results had an excellent reproducibility. The measurements were conducted at a
deposition potential of -1.0 V for 60 s and an equilibration time of 15 s. A ‘cleaning step’ at a
potential of -0.45 V for 15 s was carried out before any further measurements took place. A
square-wave voltammetric scan was applied at 25 Hz, a potential step of 4 mV and amplitude
of 25 mV [4]. It was concluded that an ex situ prepared antimony film electrode (SbFE) reacts
similarly to an in situ prepared SbFE, as well as similar to electrodes based on bismuth or
mercury while using stripping voltammetry. Its practicality in acidic solutions with pH values
of approx. 2 and in the presence of dissolved oxygen was mentioned as the biggest advantage
Validation of electroanalytical method with antimony electrode for trace metal analysis
13
of SbFE electrodes. Furthermore, the SbFE produced better results, similar to those of mercury
electrodes, regarding hydrogen evolution if compared to bismuth electrodes [4].
Hočevar et al. [12] were the first to introduce an SbFE as a possible alternative for
electrochemical stripping analysis of trace heavy metals. The method they used is similar to the
method used in this thesis. The SbFE was prepared in situ on a glassy carbon substrate electrode
and employed in combination with either ASV or stripping chronopotentiometry (SCP) in
nondeaerated solutions of 0.01 M HCl with a pH value of 2. The parameters under which the
measurements were conducted were furthermore optimised. These include the composition of
the measurement solution, the deposition time and deposition potential. As with the previous
article, the results have shown that the electrode is useful for Cd(II) and Pb(II) analysis with a
minimal effect on the environment. A good linear behaviour was reported in the concentration
range between 20 µg L-1and 140 µg L-1 for both tested ions. The LOD for Cd(II) was at
0.7 µg L-1 and 0.9 µg L-1 for Pb(II) after a 120 s deposition time. RSD was ±3.6 % for Cd(II)
and ±6.2 % for Pb(II) (60 µg L-1). The measurements were conducted at a deposition potential
of -1.2 V and an equilibration time of 15 s. The cleaning step was carried out for 30 s at a
potential of +0.3 V [12]. It was concluded that the electrode produces similar results while
analysing Cd(II) and Pb(II) particles as bismuth and mercury electrodes in combination with
ASV and SCP. The electrode’s results were reproducible. It was also noted that the SbFE
exhibits a very small signal for the reoxidation of antimony and provides markedly lower
background characteristics [12].
1.6. The Hypothesis, purpose and goal of the thesis
The purpose of this thesis is to perform a validation of the SWASV method at different
deposition potentials using antimony film modified glassy carbon electrode (SbFGCE) for
Pb(II) and Cd(II) analysis.
Validation of electroanalytical method with antimony electrode for trace metal analysis
14
2. Analytical method
2.1. Square-wave anodic stripping voltammetry (SWASV) In this work ASV was employed.
ASV is executed in several steps:
1. The electrodeposition step: The metal ion is preconcentrated and deposited on the
electrode as an alloy [13].
2. Equilibration time: The mixing of the solution is turned off after a specific amount
of time has passed. The potential does not change during the equilibration step,
which prevents the reoxidation of the metal [13].
3. Stripping: In the final step, the deposited metal on the electrode begins to oxidise
during the stripping process, transforming it back into its ionic form and thus
removing it from the electrode and back into the solution [13].
Figure 2-1: An example of anodic stripping voltammogram
In combination with ASV, square-wave voltammetry (SWV), also known as square-wave
anodic stripping voltammetry (SWASV) was used. The wave form used in SWV consists of
symmetrical square waves that are superimposed on a staircase waveform. The forward pulse,
which goes in the same direction as the scan, coincides with the staircase step. The reverse pulse
occurs halfway through the staircase step [14].
Validation of electroanalytical method with antimony electrode for trace metal analysis
15
Figure 2-2: (A) potential waveform, (B) one potential cycle, (C) voltammogram in SWV.
The response consists out of a forward (anodic, ψf), backward (cathodic, ψb) and net (ψnet)
component [15].
τ represents time and is used to describe the time needed for one square-wave cycle or one
staircase step in seconds [14]. The height of a single potential step is referred to as square wave
amplitude (Esw) [15]. Two Esw are equal to the peak-to-peak amplitude [14]. Relative to the
direction of the staircase ramp, we can recognise that the pulses with odd serial numbers are
forward pulses and the ones with even serial numbers are backwards pulses. In one cycle, the
reaction on the electrode is driven both in anodic and cathodic directions, thus providing an
insight into the electrode’s mechanism [15]. We can interpret the voltammetric data in terms of
τ, 𝑡p (duration of a single potential pulse 𝑡p = 𝜏2⁄ ), or the frequency of the potential
modulation, which is measured in Hz and defined as 𝑓 = 1𝜏⁄ [14, 15]. The overall modulation
can be represented by the scan rate (υ, defined as 𝜐 = 𝑓 ∆𝐸, ∆𝐸 – step of the staircase) [15].
The current is sampled at the end of each pulse, twice in one cycle. This technique discriminates
against the charging current by delaying the current measured at the end of each pulse [14]. The
forward and backward components are plotted against the potential of the staircase ramp. This
means that for each potential step, two currents are assigned. Further on the forward and
backward currents were substracted of a single potential pulse, obtaining a net current value.
The net currents corresponding to each potential cycle compose the net component of the
square-wave voltammogram [15].
Validation of electroanalytical method with antimony electrode for trace metal analysis
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3. Experimental
Mesurements were performed with PalmSens EIS3 potentiostat/galvanostat controlled by
the program PSTrace (PalmSens BV, Hauten, Netherlands). The GCE electrode was prepared
before the experiment by polishing it on a polishing cloth (TriDent, PSA, 2.875 in, provided by
Buehler, Lake Bluff, IL, USA) (Figure 3-1) with a thin layer of paste gained by mixing ultrapure
water (Milli-Q, Millipore Corporation, Massachusetts, USA, resistance 18.2 MΩ cm) and
aluminium oxide (0.05 µm, provided by Buehler, Lake Bluff, IL, USA). Afterwards it was
thoroughly washed with ultrapure water. After the entire apparatus was assembled by
connecting the working, counter and reference electrodes with the potentiostat/galvanostat,
20.0 mL of 0.1 M HCl, was poured into the electrochemical cell to clean the electrodes for 900 s
at a potential of +0.6 V. By doing so, possible impurities were oxidized on the electrode, which
consequently diffused into the solution. After cleaning, the electrode was tested via
hexacyanoferrate, in order to determine if it provides the expected reversible response. All
potentials reported herein are vs. Ag/AgCl (KCl saturated) reference electrode.
Figure 3-1: Polishing cloth and the aluminium oxide paste
The electrochemical cell in which the samples were analysed was always thoroughly
cleaned with 0.1 M HCl and ultrapure water. All measurements were carried out in the same
cell under the same laboratory conditions to ensure repeatable testing conditions.
Sb(III) standard solution (1000.0 mg L-1) was provided by Merck KGaA (Darmstadt,
Germany). It was diluted to 500.0 µg L-1 in 0.01 M HCl and used as an electrolyte. All
measurements were performed in a 20.0 mL solution.
Pb(II) and Cd(II) standard solutions (1000.0 mg L-1), provided by Merck KGaA
(Darmstadt, Germany) were used for the metal trace analysis. They were diluted in 0.01 M HCl
as required.
HCl solutions were prepared by diluting a 37 % HCl (provided by Carlo Erba Reagents, Val
de Reuil, France) solution with ultrapure water.
SWASV analysis was performed under the following conditions:
- Conditioning potential: 0.6 V
- Conditioning time: 30 s
- Deposition time: 60 s
Validation of electroanalytical method with antimony electrode for trace metal analysis
17
- Equilibration time: 15 s
- Starting potential: -1.2 V, -1.1 V and -1.0 V
- Final potential: 0.6 V
- Potential step: 0.004 V
- Amplitude: 0.025 V
- Frequency: 25.0 Hz
- Potential standby: 0.6 V
- Standby time: 60 s
3.1. Cyclic voltammetry (CV)
After the cleaning procedure of the working electrode, a test with potassium ferricyanide
was performed. The method in use was cyclic voltammetry (CV), it was needed to check if the
electrode was working properly.
As the potential was sweeped in to the more positive potentials, the Fe(CN)6−3 was
generated from Fe(CN)6−4 as a part of the anodic process. When the potential scan was sweeped
in to the more negative potentials, the latter was produced via a reduction of Fe(CN)6−3. This
was the cathodic process [16].
Anodic peak process: Fe(CN)6−4 → Fe(CN)6
−3 + e-
Cathodic peak process: Fe(CN)6−3 + e- → Fe(CN)6
−4
To check if the GCE electrode is working appropriately, the following analysis was
performed:
- The plot of the peak current (Ip) vs. the square root of the scan rate (𝜐1/2) had to be
linear, to ensure a diffusion controlled electrode reaction [17].
- Value of the peak potential (Ep): because of the fast electron transfer, the 𝐸p value is
independent of the scan rate, indicating a reversible electrode reaction. For that to be
true, the difference between the anodic peak potential (Epa) and the cathodic peak
potential (Epc) must be around 59 mV/n (n is number of electrons) [16, 17].
- The ratio between the anodic current peak (ipa) and cathodic current peak (ipc) is unity
[16].
An example of such analysis is given in Table 3-1.
Table 3-1: Results were similar to the proposed guidelines mentioned above
Scan rate (mV/s) Square root of
the scan rate
Peak potential difference
[∆𝐸p = 𝐸pa−𝐸pc]
Peak current ratio 𝑖pa
𝑖pc
10.00 3.16 0.084 1.08
20.00 4.47 0.076 1.07
50.00 7.07 0.084 1.08
75.00 8.66 0.092 1.08
125.00 11.18 0.100 1.09
150.00 12.25 0.100 1.09
175.00 13.23 0.104 1.09
200.00 14.14 0.108 1.09
Validation of electroanalytical method with antimony electrode for trace metal analysis
18
Figure 3-2: The linear plot of the peak current vs. square root of the scan rate, which
indicates that the reaction is controlled by diffusion.
Figure 3-3: Cyclic voltammogram of potassium ferricyanide, at different scan rates given
in Table 3-1, starting with 10 mV/s and increasing to 200 mV/s.
Increasing
scan rate
Validation of electroanalytical method with antimony electrode for trace metal analysis
19
3.2. Materials
A GCE (glassy carbon electrode, Metrohm AG, type 6.1204.300, Herisau, Switzerland) was
used as the working electrode together with an Ag/AgCl (KCl-saturated, Metrohm AG,
potential compared to standard hydrogen electrode (SHE) is 0.197 V, at 25°C) as a reference
electrode, and platinum wire (Metrohm AG) as a counter electrode. All glassware was provided
by Metrohm.
Validation of electroanalytical method with antimony electrode for trace metal analysis
20
4. Results and discussion
4.1. LOD and LOQ analysis The experiments were conducted at three deposition potentials: -1.2 V, -1.1 V and -1.0 V
vs. Ag/AgCl.
After several cleaning repetitions of the electrochemical cell, replacements of the working,
reference and counter electrodes with identical newer ones, repeated preparation of all
chemicals and replacement of the glassware, the signal for both heavy metal ions in the blank
solution was still significant. This is shown in Figure 4-1.
Figure 4-1: The reduction peaks for Cd(II) (at -0.75 V) and Pb(II) (at -0.36 V)in the blank
0.01 M HCl solution using different deposition potentials: -1.0 V (blue curve), -1.1 V (red
curve) and -1.2 V (green curve).
The first suspicion was that the ultrapure water was contaminated, so the HPLC-grade water
(Sigma-Aldrich, St. Louis, Missouri, USA) was used for both cleaning and preparing a new
solution instead, but the signals for Cd(II) and Pb(II) in the blank solution remained unchanged.
Another reason for such an occurrence could have been the presence of heavy metals in the
acid, therefore we used ultrapure HCl acid to prepare solutions (34 %-37 %, Carlo Erba
Reagents, Milano, Italy) instead. The results with ultrapure HCl acid are presented in
Figure 4-2.
Validation of electroanalytical method with antimony electrode for trace metal analysis
21
Figure 4-2: The reduction peaks for Cd(II) (at -0.75 V) and Pb(II) (at -0.33 V) in the blank
solution in ultrapure HCl acid using different deposition potentials: : -1.0 V (blue
curve), -1.1 V (red curve) and -1.2 V (green curve).
When using the ultrapure HCl acid, the reduction peaks for both metal ions in blank
solution barely changed and were still significant, thus concluding that the LOD and LOQ could
not be determined with sufficient certainty and are therefore not reported herein. However,
LOQ is certainly at a lower concentration than 14.6 µg L-1 which is the lowest concentration
limit employed for linear calibration plot.
Validation of electroanalytical method with antimony electrode for trace metal analysis
22
4.2. Linearity
Figure 4-3 shows current vs. γ response in the concentration range from 1.0 µg L-1 to
106.3 µg L-1 for Pb(II).
Figure 4-3: Concentration range for Pb(II) from 1.0 µg L-1 to 106.3 µg L-1. Points
represent values at different deposition potentials, blue at -1.2 V, orange at -1.1 V and gray at
-1.0 V.
Figure 4-4 shows current vs. γ response in the concentration range from 1.0 µg L-1 to
106.3 µg L-1 for Cd(II).
Figure 4-4: Concentration range for Cd(II) from 1.0 µg L-1 to 106.3 µg L-1. Points
represent values at different deposition potentials, blue at -1.2 V, orange at -1.1 V and gray at
-1.0 V.
Validation of electroanalytical method with antimony electrode for trace metal analysis
23
The method is linear for both Cd(II) (Figures 4-5 through 4-7) and Pb(II) (Figures 4-8
through 4-10) in the concentration range from 14.6 µg L-1 to 100.0 µg L-1. R2 greater than 0.98
was employed as a validation protocol.
Figure 4-5: Three replicates for the resulting calibration plot linear for Cd(II) response at
a -1.2 V deposition potential. Linearity regression analysis parameters for all three replicates
are given in Table 4-1.
Table 4-1: Linearity regression analysis of Cd(II) plot at a -1.2 V deposition potential for all three curves.
Date and line color Linear correlation Correlation coefficient
31.3.2017 (grey line) y = 0.1313x - 1.0718 R² = 0.99
13.4.2017 (blue line) y = 0.1235x - 0.5653 R² = 0.99
24.4.2017 (orange line) y = 0.1589x - 0.3841 R² = 0.99
Figure 4-6: Three replicates for the resulting calibration plot linear for Cd(II) response at
a -1.1 V deposition potential. Linearity regression analysis parameters for all three replicates
are given in Table 4-2.
Validation of electroanalytical method with antimony electrode for trace metal analysis
24
Table 4-2: Linearity regression analysis of Cd(II) plot at a -1.1 V deposition potential for all three curves.
Date and line color Linear correlation Correlation coefficient
31.3.2017 (grey line) y = 0.1527x - 1.3477 R² = 0.99
13.4.2017 (blue line) y = 0.1509x - 0.9431 R² = 0.98
24.4.2017 (orange line) y = 0.1874x - 0.9620 R² = 0.99
Figure 4-7: Three replicates for the resulting calibration plot linear for Cd(II) response at
a -1.0 V deposition potential. Linearity regression analysis parameters for all three replicates
are given in Table 4-3.
Table 4-3: Linearity regression analysis of Cd(II) plot at a -1.0 V deposition potential for all three curves.
Date and line color Linear correlation Correlation coefficient
31.3.2017 (grey line) y = 0.1644x - 2.0007 R² = 0.99
13.4.2017 (blue line) y = 0.1638x - 1.8404 R² = 0.99
24.4.2017 (orange line) y = 0.1963x - 1.7567 R² = 0.99
Validation of electroanalytical method with antimony electrode for trace metal analysis
25
Figure 4-8: Two replicates for the resulting calibration plot linear for Pb(II) response at
a -1.2 V deposition potential. Linearity regression analysis parameters for both replicates are
given in Table 4-4.
Table 4-4: Linearity regression analysis of Pb(II) plot at a -1.2 V deposition potential for both curves.
Date and line color Linear correlation Correlation coefficient
13.4.2017 (blue line) y = 0.133x - 1.6801 R² = 0.99
24.4.2017 (orange line) y = 0.1514x - 1.3826 R² = 0.99
Figure 4-9: Two replicates for the resulting calibration plot linear for Pb(II) response at
a -1.1 V deposition potential. Linearity regression analysis parameters for both replicates are
given in Table 4-5.
Table 4-5: Linearity regression analysis of Pb(II) plot at a -1.1 V deposition potential for both curves.
Date and line color Linear correlation Correlation coefficient
13.4.2017 (blue line) y = 0.1417x - 1.7109 R² = 0.99
24.4.2017 (orange line) y = 0.1563x - 1.6190 R² = 0.99
Validation of electroanalytical method with antimony electrode for trace metal analysis
26
Figure 4-10: Two replicates for the resulting calibration plot linear for Pb(II) response at
a -1.1 V deposition potential. Linearity regression analysis parameters for both replicates are
given in Table 4-6.
Table 4-6: Linearity regression analysis of Pb(II) plot at a -1.0 V deposition potential for both curves.
Date and line color Linear correlation Correlation coefficient
13.4.2017 (blue line) y = 0.1283x - 1.6526 R² = 0.99
24.4.2017 (orange line) y = 0.1388x - 1.6768 R² = 0.99
4.3. Accuracy
The accuracy was tested for 4 different concentrations, i.e. 15.0 µg L-1, 25.0 µg L-1,
30.0 µg L-1, 40.0 µg L-1, at three deposition potentials. The concentration of Cd(II) and Pb(II)
was determined using the calibration curve.
Average recovery was calculated in two steps:
- First step: Recovery = 𝛾𝑑𝑒𝑡𝑒𝑟𝑚𝑖𝑛𝑒𝑑
𝛾𝑡ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙 (4.1)
Where:
γ mass concentration
- Second step: average recovery = 1
𝑛∑ 𝑎𝑖
𝑛𝑖=1 (a1+a2+a3+…+an) (4.2)
Where:
n number of measurement
a sample
∑ sum
Calibration curves in use are shown in Figures 4-11 through 4-16.
Validation of electroanalytical method with antimony electrode for trace metal analysis
27
Figure 4-11: Calibration curve for Cd(II) at a deposition potential of -1.2 V.
Figure 4-12: Calibration curve for Cd(II) at a deposition potential of -1.1 V.
Validation of electroanalytical method with antimony electrode for trace metal analysis
28
Figure 4-13: Calibration curve for Cd(II) at a deposition potential of -1.0 V.
Figure 4-14: Calibration curve for Pb(II) at a deposition potential of -1.2 V.
Figure 4-15: Calibration curve for Pb(II) at a deposition potential of -1.1 V.
Validation of electroanalytical method with antimony electrode for trace metal analysis
29
Figure 4-16: Calibration curve for Pb(II) at a deposition potential of -1.0 V.
Tables from 4-7 to 4-10, show the results for accuracy (recovery) and corresponding RSD.
Table 4-7: Recovery determined for concentration at 15.0 µg L-1
Measurement Deposition
potential Recovery Pb(II) [%] Recovery Cd(II) [%]
1
-1.2 V 113.86 73.26
-1.1 V 119.29 81.99
-1.0 V 120.20 97.18
2
-1.2 V 111.18 114.45
-1.1 V 113.39 113.05
-1.0 V 118.20 126.60
3
-1.2 V 104.06 107.02
-1.1 V 106.39 106.35
-1.0 V 100.03 111.41
4
-1.2 V 106.02 113.19
-1.1 V 104.32 106.51
-1.0 V 106.33 119.75
5
-1.2 V 122.59 123.80
-1.1 V 125.20 122.44
-1.0 V 131.43 124.09
6
-1.2 V 108.43 96.41
-1.1 V 115.85 96.72
-1.0 V 111.49 101.68
Average recovery Pb(II)
[%]
Average recovery Cd(II)
[%]
-1.2 V 111.02 104.69
-1.1 V 114.07 104.51
-1.0 V 114.61 113.45
RSD [%]
Validation of electroanalytical method with antimony electrode for trace metal analysis
30
-1.2 V 6.00 17.06
-1.1 V 6.89 13.32
-1.0 V 9.70 10.67
Table 4-8: Recovery determined for concentration at 25.0 µg L-1
Measurement Deposition
potential Recovery Pb(II) Recovery Cd(II)
1
-1.2 V 93.93 109.49
-1.1 V 81.89 105.35
-1.0 V 79.91 116.84
2
-1.2 V 97.53 121.62
-1.1 V 91.00 109.19
-1.0 V 85.62 122.91
3
-1.2 V 86.47 113.72
-1.1 V 81.65 104.46
-1.0 V 75.77 107.68
4
-1.2 V 87.22 100.53
-1.1 V 82.32 96.52
-1.0 V 79.25 109.02
5
-1.2 V 90.78 89.89
-1.1 V 88.68 86.88
-1.0 V 93.06 93.77
Average recovery Pb(II) Average recovery Cd(II)
-1.2 V 91.19 107.05
-1.1 V 85.11 100.48
-1.0 V 82.72 110.04
RSD [%]
-1.2 V 5.08 11.44
-1.1 V 5.17 8.85
-1.0 V 8.19 9.99
Table 4-9: Recovery determined for concentration at 30.0 µg L-1
Measurement Deposition
potential Recovery Pb(II) Recovery Cd(II)
1
-1.2 V 100.13 97.36
-1.1 V 97.24* 93.11
-1.0 V 89.88 99.37
2
-1.2 V 117.18 120.26
-1.1 V 115.96 111.74
-1.0 V 88.09 102.01
3
-1.2 V 107.25 106.93
-1.1 V 119.27 106.09
-1.0 V 108.90 121.43
4
-1.2 V 130.40 132.94
-1.1 V 118.97 126.36
-1.0 V 106.17 132.64
Validation of electroanalytical method with antimony electrode for trace metal analysis
31
5
-1.2 V 117.07 127.93
-1.1 V 112.98 121.16
-1.0 V 92.38 131.51
6
-1.2 V 141.20 138.54
-1.1 V 121.31 127.42
-1.0 V 93.06 138.95
Average recovery Pb(II) Average recovery Cd(II)
-1.2 V 118.87 120.66
-1.1 V 117.70 114.32
-1.0 V 96.41 120.99
RSD [%]
-1.2 V 12.60 13.13
-1.1 V 2.80 11.65
-1.0 V 9.20 13.82
*Outlier according to Grubbs’ and Dixon’s test
Table 4-10: Recovery determined for concentration at 40.0 µg L-1
Measurement Deposition
potential RecoveryPb(II) Recovery Cd(II)
1
-1.2 V 115.29 101.58
-1.1 V 103.58 96.71
-1.0 V 84.90 102.75
2
-1.2 V 105.07 95.98
-1.1 V 93.36 90.65
-1.0 V 83.69 98.71
3
-1.2 V 130.05 118.67
-1.1 V 108.66 113.65
-1.0 V 81.47 123.90
4
-1.2 V 96.42 104.91
-1.1 V 90.79 98.45
-1.0 V 71.65 107.74
5
-1.2 V 99.64 106.94
-1.1 V 94.12 101.93
-1.0 V 73.92 112.62
6
-1.2 V 91.83 99.79
-1.1 V 85.86 95.78
-1.0 V 79.17 113.33
Average recovery Pb(II) Average recovery Cd(II)
-1.2 V 106.38 105.26
-1.1 V 96.06 100.09
Validation of electroanalytical method with antimony electrode for trace metal analysis
32
-1.0 V 79.13 111.26
RSD [%]
-1.2 V 13.28 7.53
-1.1 V 8.81 7.88
-1.0 V 6.75 8.10
The data in the Tables 4-7 through 4-10 confirms that the tested method is both accurate
and precise.
All RSD values are below the prescribed 20% value, proving the method’s precision [18].
The accuracy was proven via average recovery, which was mainly in the limits, between 80%
and 120% [18], except for Cd(II) at deposition potentials of -1.0 V and -1.2 V at 40.0 µg L-1
and Pb(II) at the deposition potential of -1.0 V also at 40.0 µg L-1. When testing the method for
outliers, only one such measurement was found for Pb(II) at the deposition potential of -1.1 V
at the concentration of 30.0 µg L-1. The data shows that the method works best when used with
the deposition potential -1.1 V for both Pb(II) and Cd(II).
Validation of electroanalytical method with antimony electrode for trace metal analysis
33
5. Conclusion
This work presents the validation of the SWASV technique with a glassy carbon electrode
modified with antimony film for trace metal analysis. Antimony film was prepared in situ. This
method showed good electroanalytical performance for Cd(II) and Pb(II) trace analysis.
It was determined that the method is linear in the concentration range from 14.6 µg L-1 to
100.0 µg L-1 for simultaneous analysis of both Pb(II) and Cd(II). The limit of detection and the
limit of quantification were not determined, due to HCl solution impurity.
The accuracy of the method was tested for four different concentrations, i.e. 15.0 µg L-1,
25.0 µg L-1, 30.0 µg L-1 and 40.0 µg L-1. It was found out that the average recovery values for
all three deposition potentials, excluding Cd(II) at deposition potentials of -1.0 V and -1.2 V at
40.0 µg L-1 and Pb(II) at the deposition potential of -1.0 V also at 40.0 µg L-1, were within the
prescribed interval (between 80 % and 120 %), thus proving the method as accurate. All RSD
values were under the limit of 20 %, thus indicating that the method is precise. The gathered
data shows, that the method works best when used with the deposition potential -1.1 V vs.
Ag/AgCl for both Pb(II) and Cd(II)
To conclude, the method using SbFE, as it stands today, is very useful for the detection and
measurements of trace Cd(II) and Pb(II) in acidic solutions. With further research and
optimisation it will become an even better alternative to the standard mercury electrode and will
stand on par with the bismuth electrode. In the future, however, more research needs to be done
on other electrodes, using elements such as copper to broaden the range of potential electrodes
that will be able to replace the mercury electrode once and for all.
Validation of electroanalytical method with antimony electrode for trace metal analysis
34
6. References
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http://www.lenntech.com/processes/heavy/heavy-metals/heavy-metals.htm.
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8. Trbojević, J., Določanje železa z atomsko absorpcijsko spektrometrijo (validacija
metode). 2016. p. 47.
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http://webspace.ship.edu/pgmarr/Geo441/Lectures/OPT%201%20-
%20Outlier%20Detection.pdf.
10. Zupan, J., Kemometrija in obdelava eksperimentalnih podatkov. 2009, Ljubljana,
Slovenija: Inštitut nove revije, zavod za humanistiko in Kemijski inštitut.
11. StatisticHowTo. Relative Standard Deviation: Definition & Formula. Access
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12. Hocevar, S.B., et al., Antimony Film Electrode for Electrochemical Stripping Analysis.
Analytical Chemistry, 2007. 79(22): p. 8639-8643.
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from: https://www.tau.ac.il/~advanal/StrippingVoltammetry.htm.
14. Research, P.A. Application Note S-7, Square wave Voltammetry. Access
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15. Mirceski, V., et al., Square-Wave Voltammetry: A Review on the Recent Progress.
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16. Marasinghe, A. Cyclic Voltammetric Study of ferrocyanide/ferricyanide Redox
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Validation of electroanalytical method with antimony electrode for trace metal analysis
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7. Življenjepis (CV)
Aljaž Ramot
Ciril-Metodov drevored 5, 2250 Ptuj
E-MAIL: [email protected] GSM: +38631-311-250
Kratek opis:
Star sem 22let. Sem komunikativen, socialen in vedno željan novih izkušenj, ter izzivov. Poglabljam se predvsem v
področje znanosti, komunikacij in novih tehnologij, s katerimi sem rad na tekočem. Večkrat sem se srečal tudi z javnim
nastopanjem, tako v sklopu izobraževanja kot tudi izven. Opravljeno imam gimnazijsko maturo z odličnim uspehom,
trenutno pa študiram kemijsko tehnologijo na Univerzi v Mariboru.
S področja kemije in kemijske analitike imam že nekaj izkušenj. Z delom v tej smeri sem pričel z raziskovalno nalogo
v srednji šoli, nadaljeval s fakultativnim izobraževanjem, prakso in delom za diplomsko nalogo.
Izkušnje imam tudi iz področja dela z ljudmi, saj 4 leta delam kot cestninski blagajnik pri podjetju DARS,
preko študentske napotnice.
eleno delovno mesto:
Želim si delovnega mesta, kjer bom lahko širil svoj spekter znanj, spoznaval nove tehnologije in se udejanjil v najboljši meri.
Sam sem prilagodljiv, zato mi delo v kolektivu ne povzroča nevšečnosti. Sem organiziran, zato mi tudi večji obseg delovnih
nalog ne predstavlja težav.
Delovne izkušnje
Raziskovalno
delo
Prve izkušnje na področju raziskovalnega dela, sem pridobil v srednji šoli, ko sem s pomočjo
raziskovalne naloge, Meritve koncentracij in velikosti nanodelcev na Gimnaziji Ptuj, spoznal
kemijsko analizo in osvojil zlato priznanje Zveze za tehnično kulturo Slovenije (ZOTKS).
V času študija sem sodeloval pri projektu Inovativne analize genoma in biooznačevalcev za
boljše diagnosticiranje in zdravljenje bolnikov s kroničnimi vnetnimi črevesnimi boleznimi
(GenBioKVČB), ki je potekal v sodelovanju z Medicinsko fakulteto Univerze v Mariboru.
Praktično
usposabljanje
V sklopu predmeta na fakulteti, sem opravljal praktično usposabljanje v podjetju Talum inštitut
d.o.o. Tam sem se srečal s številnimi tehnikami analize vod, odpadkov in plinov.
Diplomsko delo V sklopu diplomskega dela, validacija elektroanalizne metode z antimonovo elektrodo za
analizo težkih kovin v sledovih, sem opravljal analize in se spoznal s programom PSTrace.
Validation of electroanalytical method with antimony electrode for trace metal analysis
36
Moje osrednje lastnosti: Komunikativnost, organiziranost, odgovornost, samoiniciativnost, sposobnost dela v kolektivu, retorične sposobnosti,
iznajdljivost, poštenost, vztrajnost
Kronološki pregled dosedanjih delovnih mest: 2013 - 2017 Dars d.d.
Cestninski blagajnik
5.2017 – 9.2017 Vitiva d.d.
Pomoč pri vzdrževanju
Izobrazba
2009 – 2013 Gimnazija Ptuj
2013 – 2017
2017- predvidoma
2019
Univerza v Mariboru,
Smer: Kemijska tehnologija (VS)
Univerza v Mariboru
Smer: Kemijska tehnika
Dodatna izobraževanja
2012 - 2013 Deutsche Sprachdiplom
2010, 2011, 2012 English camp (Društvo več)
Druga znanja in veščine
Tuji jeziki: Angleščina (razumevanje: odlično, branje: odlično, pisanje: odlično)
Nemščina (razumevanje: odlično, branje: odlično, pisanje: dobro)
Hrvaščina (razumevanje: odlično, branje: odlično, pisanje: dobro)
Delo z računalnikom: Okolje Windows, MS Office (Word, Excel, PowerPoint, Paint) (poznavanje: odlično,
uporaba: vsak dan)
Google Documents (poznavanje: odlično, uporaba: večkrat tedensko)
PSTrace (poznavanje: dobro, uporaba: v času diplomskega dela)
Cubase (poznavanje: dobro, uporaba: občasno)
Videopad (poznavanje: dobro, uporaba: občasno)
AutoCAD (poznavanje: osnovno, uporaba: občasno)
Hobiji: Atletika, montaža audi in video posnetkov, v prostem času igram v glasbeni skupini
Vozniški izpit B - kategorija, lastni prevoz