New voltammetric strategy for determination of dopamine in the presence of high concentrations of acetaminophen, folic acid and N-acetylcysteine

Article abstract of DOI:10.1016/j.molliq.2012.02.008

A new electrochemical sensor for the simultaneous determination of dopamine (DA), acetaminophen (AC), folic acid (FA) and N-acetylcysteine (NAC) is described. The sensor is based on carbon-paste electrode (CPE) modified with 5-amino-3′,4′-dimethyl -biphenyl-2-ol (5ADB) and takes the advantages of carbon nanotubes (CNTs), which makes the modified electrode highly sensitive for the electrochemical detection of these compounds. Under the optimum pH of 7.0, the oxidation of DA occurs at a potential about 170 mV less positive than that of the unmodified CPE. Also, square wave voltammetry was used for the simultaneous determination of DA, AC, FA and NAC at the modified electrode.

Full text of DOI:10.1016/j.molliq.2012.02.008

Journal of Molecular Liquids 169 (2012) 130–135
Contents lists available at SciVerse ScienceDirect
Journal of Molecular Liquids
journal homepage: www.elsevier.com/locate/molliq
New voltammetric strategy for determination of dopamine in the presence of high
concentrations of acetaminophen, folic acid and N-acetylcysteine
b
b
c
Hadi Beitollahi a, , Alireza Mohadesi , Somayeh Mohammadi , Ali Pahlavan ,
⁎
Hassan Karimi-Maleh d, Ali Akbari b
a
Environment Department, Research Institute of Environmental Sciences, International Center for Science, High Technology & Environmental Sciences, Kerman, Iran
Department of Chemistry, Payame Noor University, 19395-4697, Tehran, I.R. of Iran
Department of Physics, Science and Research Branch, Islamic Azad University, Mazandaran, Iran
Department of Chemistry, Science and Research Branch, Islamic Azad University, Mazandaran, Iran
b
c
d
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 28 January 2012
Received in revised form 14 February 2012
Accepted 15 February 2012
Available online 28 February 2012
A new electrochemical sensor for the simultaneous determination of dopamine (DA), acetaminophen (AC),
folic acid (FA) and N-acetylcysteine (NAC) is described. The sensor is based on carbon-paste electrode
(CPE) modified with 5-amino-3′,4′-dimethyl -biphenyl-2-ol (5ADB) and takes the advantages of carbon
nanotubes (CNTs), which makes the modified electrode highly sensitive for the electrochemical detection
of these compounds. Under the optimum pH of 7.0, the oxidation of DA occurs at a potential about 170 mV
less positive than that of the unmodified CPE. Also, square wave voltammetry was used for the simultaneous
determination of DA, AC, FA and NAC at the modified electrode.
Keywords:
Dopamine
Acetaminophen
Folic acid
© 2012 Elsevier B.V. All rights reserved.
N-acetylcysteine
Carbon nanotube
Modified carbon-paste electrode
1. Introduction
oxidation had been reported widely with the advantages of simplici-
ty, high speed and sensitivity [9–13].
Since the electrochemical properties of carbon nanotubes (CNTs)
have been unveiled, their application in electrochemical sensors and
biosensors has gained much attention [1,2]. Recent studies demon-
strated that CNTs have a high electrocatalytic effect and a fast electron-
transfer rate [3–6]. CNTs-modified electrodes can accumulate important
biomolecules and alleviate surface fouling effects.
Dopamine (DA) is one of the most important catecholamine neu-
rotransmitters in the mammalian central nervous system. Abnormal-
ities in DA concentrations have been linked with several neurological
disorders such as the debilitating ailment Parkinson's disease and the
mental disorder schizophrenia [7]. DA is also believed to play a cen-
tral role in Huntington's disease, a fatal genetic neurodegenerative
movement disorder and has also been associated with drug addiction
and attention disorders [8]. Therefore, DA has been given tremendous
consideration in biomedical investigation and there is a strong need
to establish sensitive, selective and reliable methods for the direct
measurement of DA. Since DA is an electroactive compound and can
be easily oxidized, the electroanalysis of DA based on the electro-
Acetaminophen (AC) is a widely used anti-pyretic and analgesic
drug with actions similar to aspirin. It is an effective and safe agent for
the relief of mild to moderate pain associated with headache, arthritis
and postoperative pain. Its ready access has resulted in its increased
use in attempted suicide [14]. Among different methods for determina-
tion of AC, electrochemical methods maybe the most widely applied be-
cause of high sensitivity, simplicity and reproducibility of this approach
[15–19].
Several chronic diseases (for example, gigantocytic anemia, leu-
copoenia, mentality devolution, psychosis, heart attack, and stroke),
especially those concerned with malformation during pregnancy
and carcinogenic processes, are related to the deficiency of folic
acid (FA) [20] which is a water-soluble vitamin. Since FA is detected
in biological fluids at low concentration, a highly specific and sensi-
tive assay is called for. As FA is an electroactive component, some
electrochemical methods have been reported for its determination
[21–25].
N-acetylcysteine (NAC) is an endogenous antioxidant acting as a
free radical scavenger and precursor of glutathione synthesis. This re-
activity makes NAC a powerful antioxidant and a potentially thera-
peutic agent in the treatment of cancer, cardiovascular and
respiratory diseases, human immunodeficiency virus (HIV) infection,
acetaminophen toxicity, neurodegenerative disorder and other
⁎
Corresponding author. Tel.: +98 3426226613; fax: +98 3426226617.
E-mail address: h.beitollahi@yahoo.com (H. Beitollahi).
0167-7322/$ – see front matter © 2012 Elsevier B.V. All rights reserved.
doi:10.1016/j.molliq.2012.02.008

H. Beitollahi et al. / Journal of Molecular Liquids 169 (2012) 130–135
131
diseases characterized by free radicals production and oxidative dam-
age [26–30].
AC electrophysiological [31] effects support the idea that this po-
2. Experimental
2.1. Apparatus and chemicals
tent analgesic drug can act in the central nervous system (CNS). An-
imal model studies have shown that AC might protect neurons from
degeneration. For example, AC can protect primary rat embryonic DA
neurons from glutamate toxicity [32]. Also, AC administration at
antinociceptive doses affects serotonin (5-HT) and DA levels in vari-
ous brain areas and the spinal cord in rats [33]. Additionally, impor-
tant drugs such as AC will interfere with DA measurements in
biological samples [34]. Thus, it is necessary to develop low-cost,
simple, reproducible and reliable methods for simultaneous deter-
mination of DA and AC, which is a major goal of electroanalytical
research.
DA oxidation products such as H2O2 and reactive quinones have
been held responsible for various toxic actions of DA, which have im-
plications in the aetiopathogenesis of Parkinson's disease. Studies
have shown that NAC is a potent scavenger of both H2O2 and toxic
quinones derived from DA and it further prevents DA mediated inhi-
bition of Na+,K+-ATPase activity and mitochondrial respiratory
chain function. The quinone scavenging ability of NAC is presumably
related to its protective effect against DA mediated inhibition of mito-
chondrial respiratory chain activity. However, both H2O2 scavenging
and quinone scavenging properties of NAC probably account for its
protective effect against Na+,K+-ATPase inhibition induced by DA.
The results have important implications in the neuroprotective ther-
apy of sporadic Parkinson's disease since inactivation of mitochondri-
al respiratory activity and Na+,K+-ATPase may trigger intracellular
damage pathways leading to the death of nigral dopaminergic neu-
rons [35].
The electrochemical measurements were performed with an Autolab
potentiostat/galvanostat (PGSTAT 12, Eco Chemie, The Netherlands).
The experimental conditions were controlled with General Purpose
Electrochemical System (GPES) software. A conventional three elec-
trode cell was used at 25 1 °C. An Ag/AgCl/KCl (3.0 M) electrode
(Metrohm), a platinum wire (Metrohm), and the (5ADBCNPE) were
used as the reference, auxiliary and working electrodes, respectively. A
Metrohm 827 pH/Ion Meter was used for pH measurements.
All solutions were freshly prepared with double distilled water.
DA, AC, FA and NAC and all other reagents were of analytical grade
from Merck (Darmstadt, Germany). Graphite powder and paraffin
oil (DC 350, density=0.88 g cm−3) as the binding agent (both from
Merck) were used for preparing the pastes. Multiwalled carbon nano-
tubes (purity more than 95%) with o.d. between 10 and 20 nm, i.d.
between 5 and 10 nm, and tube length from 0.5 to 200 μm were pre-
pared from Nanostructured & Amorphous Materials, Inc. The buffer
solutions were prepared from orthophosphoric acid and its salts in
the pH range of 2.0–9.0.
2.2. Synthesis of 5-amino-3′,4′-dimethyl-biphenyl-2-ol
For preparing of the title compound, 3.02 g (20 mmol) of N-(2-
Hydroxy-phenyl)-acetamide, 3.70 g (20 mmol) of 4-bromo-o-xylene
and 2.81 g of PdCl2(PPh3)2 (bis(triphenylphosphine)palladium(II)
chloride) were placed in a 50 mL conical vial and add 20 ml of
dimethylacetamide (DMA) and 6.72 g t-BuOK. Then, a magnetic
spin vane was added to the conical vial and attached to a water-
cooled condenser. It was heated at about 90 °C for at least 12 h.
The progress of reaction was monitored by TLC. After completion of
reaction, the resulting mixture was allowed to be cooled for a few
minutes, and Pd(PPh3)4 was collected by vacuum filtration using a
Hirsch funnel. Then, chloroform was added to the mixture and fil-
tered to recover the catalyst. Acetamides are readily cleaved by bar-
ium hydroxide with >90 % yields. The crude product was
recrystallized from iso-propanol and chloroform (20:80) to afford
pure 5-amino-3',4'- dimethyl -biphenyl-2-ol with 83 % yields.
Mouse experiments suggest that FA deficiency could increase the
brain's susceptibility to Parkinson's disease, according to scientists
at the National Institute on Aging. In the finding, published in the Jan-
uary 2002 issue of the Journal of Neurochemistry, the investigators
fed one group of mice a diet that included folate, while a second
group was fed a diet lacking this vitamin. They then gave the mice
moderate amounts of MPTP, a chemical that can cause Parkinson-
like symptoms. In the mice fed folate, MPTP caused only mild symp-
toms of disease. But mice fed the folate-deficient diet developed se-
vere Parkinson-like symptoms [36].
The scientists found that mice with low amounts of dietary FA had
elevated levels of homocysteine in the blood and brain. They suspect
that increased levels of homocysteine in the brain caused damage to
the DNA of nerve cells in the substantia nigra, an important brain
structure that produces DA. Loss of DA causes the nerve cells to dys-
function, leaving patients unable to direct or control their movement
in a normal manner [37].
People who have Parkinson's disease often have low levels of FA in
their blood, but it is not clear whether this result of the disease pro-
cess or if they are simply malnourished due to their illness. But
based on this study, Dr. Mattson speculates that consuming adequate
amounts of FA-either in the diet or by supplementation-could help
protect the aging brain against Parkinson's and other neurodegenera-
tive diseases[37].
2.3. Preparation of the electrode
The 5ADBCNPEs were prepared by hand mixing 0.01 g of 5ADB
with 0.89 g graphite powder and 0.1 g CNTs with a mortar and pestle.
Then, ~0.7 mL of paraffin oil was added to the above mixture and
mixed for 20 min until a uniformly-wetted paste was obtained. The
paste was then packed into the end of a glass tube (ca. 3.4 mm i.d.
and 15 cm long). A copper wire inserted into the carbon paste provid-
ed the electrical contact. When necessary, a new surface was obtained
by pushing an excess of the paste out of the tube and polishing with a
weighing paper.
For comparison, 5ADB modified CPE electrode (5ADB-CPE) without
CNTs, CNTs paste electrode (CNPE) without 5ADB, and unmodified
CPE in the absence of both 5ADB and CNTs were also prepared in
the same way.
Therefore, simultaneous determination of DA, AC, FA and NAC is
very important, but there is not any electrochemical report about si-
multaneous determination of these four compounds.
Electroanalytical methods have attracted more attention in recent
years for environmental and biological compounds determination
due to their sensitivity, accuracy, lower cost, and simplicity [38–85].
In the present work, we describe the preparation of a new electrode
composed of CNPE modified with 5-amino-3′,4′-dimethyl -biphenyl-2-
ol (5ADBCNPE) and investigate its performance for the electrocatalytic
determination of DA in aqueous solutions. We also evaluate the analyt-
ical performance of the modified electrode for the quantification of DA
in the presence of AC, FA and NAC for the first time.
3. Results and discussion
3.1. Electrochemical properties of 5ADBCNPE
To the best of our knowledge there is no prior report on the electro-
chemical properties and, in particular, the electrocatalytic activity of
5ADB in aqueous media. Therefore, we prepared 5ADBCNPE and studied
its electrochemical properties in a buffered aqueous solution (pH 7.0)
using CV (Fig.1). It should be noted that one of the advantages of 5ADB

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H. Beitollahi et al. / Journal of Molecular Liquids 169 (2012) 130–135
Fig. 1. CVs of 5ADBCNPE in 0.1 M PBS (pH 7.0), at various scan rates, numbers 1–11 correspond to 10, 20, 50, 100, 200, 300, 400, 500, 600, 700 and 800 mV s−1. Insets: variation of
(A) Ip vs. scan rate; (B) variation of Ep versus the logarithm of the high scan rates.
as an electrode modifier is its insolubility in aqueous media. Experimen-
tal results showed reproducible, well-defined, anodic and cathodic peaks
with Epa, Epc and E°′ of 0.28, 0.18 and 0.23 V vs. Ag/AgCl/KCl (3.0 M) re-
spectively. The observed peak separation potential, ΔEp=(Epa −Epc) of
100 mV, was greater than the value of 59/n mV expected for a reversible
system [86], suggesting that the redox couple of 5ADB in 5ADBCNPE has
a quasi-reversible behavior in aqueous medium. The effect of the poten-
tial scan rate (ν) on electrochemical properties of the 5ADBCNPE was
also studied by CV. Plots of the both anodic and cathodic peak currents
(Ip) were linearly dependent on ν in the range of 10 to 800 mV s−1
(Fig. 1A), indicating that the redox process of 5ADB at the modified elec-
trode is diffusionless in nature.
3.2. Influence of pH
The electrochemistry of 5ADB molecule is generally pH dependent.
Thus, the electrochemical behavior of 5ADBCNPE was studied at differ-
ent pHs using CV (Fig. 2). It was observed that the anodic and cathodic
peak potentials of 5ADBCNPE shift to less positive values with increas-
ing pH. Inset of Fig. 2 shows potential-pH diagrams constructed by plot-
ting the anodic, cathodic and half-wave potential values as the function
of pH. As can be seen the slopes are 47.845, 49.262 and 48.298 mV/pH
The apparent charge transfer rate constant, ks, and the charge trans-
fer coefficient, α, of a surface-confined redox couple can be evaluated
from CV experiments by using the variation of anodic and cathodic
peak potentials with logarithm of scan rate, according to the procedure
of Laviron [87]. Fig. 1B shows such plots, indicating that the Ep values
are proportional to the logarithm of scan rate for ν values higher than
3 V s−1 (Fig. 1B). The slopes of the plots in Fig. 1B can be used to extract
the kinetic parameters αc and αa (cathodic and anodic transfer coeffi-
cients, respectively). The slope of the linear segments is equal to
−2.303RT/αnF and 2.303RT/(1−α)nF for the cathodic and anodic
peaks, respectively. The evaluated value for α is 0.5.
Also, Eq. (1) can be used to determine the electron transfer rate
constant between the modifier (5ADB) and CNPE:
logks ¼ αlogð1−αÞ þ ð1−αÞlogα−logðRT=nFνÞ−αð1−αÞnFΔEp=2:3RT
ð1Þ
where (1−α)nα =0.5, ν is the sweep rate and all other symbols hav-
ing their conventional meanings. The value of ks was evaluated to be
23.9 s−1 using Eq. (1).
Fig. 2. CVs (at 20 mV s−1) of 5ADBCNPE at various buffered pHs. The numbers 1–8 corre-
spond to 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, and 9.0 pHs, respectively. Inset: Plot of Epa, Epc and
E1/2 vs. pH.

H. Beitollahi et al. / Journal of Molecular Liquids 169 (2012) 130–135
133
(curve e) and 5ADBCNPE (curve f). As it is seen, while the anodic peak
potential for DA oxidation at the CNPE, and unmodified CPE are 400
and 450 mV, respectively, the corresponding potential at 5ADBCNPE
and 5ADBCPE is~280 mV. These results indicate that the peak potential
for DA oxidation at the 5ADBCNPE and 5ADBCPE electrodes shift
by~120 and 170 mV toward negative values compared to CNPE and
unmodified CPE, respectively. However, 5ADBCNPE shows much higher
anodic peak current for the oxidation of DA compared to 5ADBCPE, in-
dicating that the combination of CNTs and the mediator (5ADB) has sig-
nificantly improved the performance of the electrode toward DA
oxidation. In fact, 5ADBCNPE in the absence of DA exhibited a well-
behaved redox reaction (Fig. 3, curve c) in 0.1 M PBS (pH 7.0). However,
there was a drastic increase in the anodic peak current in the presence
of 50.0 μM DA (curve f), which can be related to the strong electrocata-
lytic effect of the 5ADBCNPE towards this compound [86].
The effect of scan rate on the electrocatalytic oxidation of DA at the
5ADBCNPE was investigated by CV (Fig. 4). Results showed, the oxida-
tion peak potential shifted to more positive potentials with increasing
scan rate, confirming the kinetic limitation in the electrochemical reac-
tion. Also, a plot of peak height (Ip) vs. the square root of scan rate (ν1/2
)
was found to be linear in the range of 4–20 mV s−1 (Fig. 4A), suggesting
that, at sufficient overpotential, the process is diffusion rather than sur-
face controlled [86].
Fig. 3. CVs of (a) unmodified CPE in 0.1 M PBS (pH 7.0), (b) unmodified CPE in 50.0 μM
DA, (c) 5ADBCNPE in 0.1 M PBS, (d) CNPE in 0.1 mM DA, (e) 5ADBCPE in 0.1 mM DA,
and (f) 5ADBCNPE in 50.0 μM DA. In all cases the scan rate was 10 mV s−1
.
The Tafel slope (b) can be obtained from the slope of Ep vs. log v
using Eq. (2) [86]:
for Epa, Epc and E1/2 respectively, indicating that the system obeys the
Nernst equation for an equal electron and proton transfer reaction [86].
Ep ¼ b=2 log v þ constant
ð2Þ
3.3. Electrocatalytic oxidation of DA at a 5ADBCNPE
The Tafel slope was found to be 108.0 mV (Fig. 4, inset B), which
indicates that a one-electron transfer process is the rate limiting
step assuming a transfer coefficient (α) is about 0.45.
Fig. 3 depicts the CV responses for the electrochemical oxidation of
50.0 μM DA at unmodified CPE (curve b), CNPE (curve d), 5ADBCPE
Fig. 4. CVs of 5ADBCNPE in 0.1 M PBS (pH 7.0) containing 10.0 μM DA at various scan rates; from inner to outer scan rates of 4, 6, 8, 10, 15 and 20 mV s−1, respectively. Insets: Variation of
(A) anodic peak current vs. ν1/2; (B) the variation of the anodic peak potential vs log v.

134
H. Beitollahi et al. / Journal of Molecular Liquids 169 (2012) 130–135
Fig. 5. SWVs of 5ADBCNPE in 0.1 M PBS (pH 7.0) containing different concentrations of DA+AC+FA+NA in μM, from inner to outer: 40.0+225.0+700.0+170.0, 100.0+300.0+
800.0+425.0, 150.0+400.0+900.0+630.0, 180.0+450.0+950.0+765.0, 225.0+500.0+1100.0+950.0, 300.0+650.0+1200.0+1275.0, 400.0+800.0+1475.0 +1700.0
and 470.0+900.0+1600.0+2000.0 respectively. Insets (A), (B), (C) and (D) plots of Ip vs. DA, AC, FA and NAC concentrations respectively.
3.4. Electrocatalytic determination of DA
490, 785 and 1030 mV, corresponding to the oxidation of DA, AC, FA
and NAC, respectively, indicating that simultaneous determination of
these compounds is feasible at the 5ADBCNPE as shown in Fig. 5.
The sensitivity of the modified electrode towards the oxidation of DA
was found to be 0.045 μA μM−1. This is very close to the value obtained in
the absence of AC, FA and NAC (0.046 μA μM−1), indicating that the
oxidation processes of these compounds at the 5ADBCNPE are
independent and therefore, simultaneous determination of their
mixtures is possible without significant interferences.
The electrocatalytic peak current of DA oxidation at the surface of the
modified electrode can be used for the determination of DA in solution.
Therefore, square wave voltammetry (SWV) experiments were per-
formed using modified electrode in phosphate buffer solution containing
various concentrations of DA. The results show that the electrocatalytic
peak current of DA oxidation at the surface of modified electrode was lin-
early dependent on the DA concentrations. The mediated oxidation peak
currents of DA at the surface of a modified electrode were proportional to
the concentration of the DA within the ranges 1.2 μM to 900.0 μM with a
current sensitivity of 0.046 μA/μM in the SWV. The detection limit (3σ)
was 0.57 μM.
3.6. Real sample analysis
One milliliter of a DA ampoule was diluted to 10 mL with PBS (0.1 M,
pH 7.0); then, a different capacity of the diluted solution was trans-
ferred into each of a series of 10 mL volumetric flasks and diluted to
the mark with PBS. Each sample solution was transferred into the elec-
trochemical cell and SWV was recorded between 0.0 and 0.5 V at a scan
rate of 10 mV s−1. The Ipa was measured at the oxidation potential of
DA and the concentration of this compound was obtained from the cal-
ibration plot. This procedure was repeated five times for each sample,
and the average amount of DA in the injection was found to be
203 mg/5 mL, a value in well agreement with the value on the ampoule
3.5. Simultaneous determination of DA, AC, FA and NAC
To our knowledge, there is no report on the simultaneous determi-
nation of DA, AC, NAC and FA using modified electrodes and specially
modified carbon nanotube paste electrodes. Therefore, the main objec-
tive of this study was to detect DA, AC, NAC and FA simultaneously using
5ADBCNPE. This was performed by simultaneously changing the con-
centrations of DA, AC, NAC and FA, and recording the SWVs. The voltam-
metric results showed well-defined anodic peaks at potentials of 285,
Table 1
Determination of DA, AC, FA and NAC in mixtures. All the concentrations are in μM (n=3).
No
DA
AC
FA
NAC
DA
AC
FA
NAC
Injection
Added
Added
Added
Found
Rec. %
RSD %
Found
Rec. %
RSD %
Found
Rec. %
RSD %
Found
Rec. %
RSD %
1
2
3
4
5
6
50.0
50.0
100.0
100.0
200.0
200.0
0
0
49.5
49.7
103.5
99.5
204.5
197.3
99.0
99.4
103.5
99.5
102.2
98.6
1.1
2.0
1.2
2.3
2.3
3.2
–
–
–
–
–
–
–
–
–
270.0
0
400.0
0
250.0
0
500.0
0
1000.0
1500.0
1900.0
269.0
–
99.6
–
3.4
–
253.9
–
101.6
–
1.9
–
1038.0
–
103.8
–
1.4
–
403.0
–
100.7
–
2.8
–
504.5
–
100.9
–
2.6
–
1550.0
–
103.3
–
2.0
–
450.0
700.0
445.9
99.1
1.1
690.2
98.6
1.5
1919.9
101.0
1.2

H. Beitollahi et al. / Journal of Molecular Liquids 169 (2012) 130–135
135
[35] S.P. Wilson, D.L. Kamin, J.M. Feldman, Clinical Chemistry 31 (1985) 1093–1094.
label (200 mg/5 mL). Also, to a series of 10 mL volumetric flasks, differ-
ent capacity of the diluted DA injection solution together with standard
AC, FA and NAC solutions were added and diluted to the mark with
phosphate buffer. The SWVs were recorded and the anodic peak cur-
rents for each of DA, AC, FA and NAC were measured at their own oxida-
tion potentials. According to the results listed in Table 1, very good
recoveries for the determinations of DA, AC, FA and NAC were obtained
with high reproducibility, which indicates that the sensor can be ap-
plied for the analysis of these compounds with no significant influence
from each other.
[36] http://neurotalk.psychcentral.com/showthread.php?p=802471.
[37] http://www.nia.nih.gov/Alzheimers/ResearchInformation/NewsReleases/Archives/
PR2002/PR20020114folicacidparkinsons.htm.
[38] V.K. Gupta, R. Jain, K. Radhapyari, N. Jadon, S. Agarwal, Analytical Biochemistry
408 (2011) 179–196.
[39] V.K. Gupta, R. Jain, S. Agarwal, R. Mishra, A. Dwivedi, Analytical Biochemistry
410 (2011) 266–271.
[40] R. Jain, V.K. Gupta, N. Jadon, K. Radhapyari, Journal of Electroanalytical Chemistry
648 (2010) 20–27.
[41] S. Chitravathi, B.E. Kumara Swamy, G.P. Mamatha, B.S. Sherigara, Journal of Elec-
troanalytical Chemistry 667 (2012) 66–75.
[42] V.K. Gupta, R. Jain, N. Jadon, K. Radhapyari, Journal of Colloid and Interface Sci-
ence 350 (2010) 330–335.
[43] V.K. Gupta, H. Khani, B. Ahmadi-Roudi, S. Mirakhorli, E. Fereyduni, S. Agarwal,
Talanta 83 (2011) 1014–1022.
4. Conclusion
[44] J.J. Colleran, C.B. Breslin, Journal of Electroanalytical Chemistry 667 (2012) 30–37.
[45] V.K. Gupta, A.K. Singh, B. Gupta, Analytica Chimica Acta 575 (2006) 198–204.
[46] A.K. Singh, V.K. Gupta, B. Gupta, Analytica Chimica Acta 585 (2007) 171–178.
[47] R. Karimi Shervedani, A. Amini, Bioelectrochemistry 84 (2012) 25–31.
[48] V.K. Gupta, R.N. Goyal, R.A. Sharma, Analytica Chimica Acta 647 (2009) 66–71.
[49] A.K. Jain, V.K. Gupta, L.P. Singh, P. Srivastava, J.R. Raisoni, Talanta 65 (2005) 716–721.
[50] T. Hoshino, S.I. Sekiguchi, H. Muguruma, Bioelectrochemistry 84 (2012) 1–5.
[51] R. Prasad, V.K. Gupta, A. Kumar, Analytica Chimica Acta 508 (2004) 61–70.
[52] V.K. Gupta, R. Ludwig, S. Agarwal, Analytica Chimica Acta 538 (2005) 213–218.
[53] S.P. Zhang, L.G. Shan, Z.R. Tian, Y. Zheng, L.Y. Shi, D.S. Zhang, Chinese Chemical
Letters 19 (2008) 592–594.
In this paper, we have constructed a novel modified carbon-paste
electrode for the detection of DA. The results of this study indicated
that the electrode exhibited linear response over a wide concentration
range (1.2 μM to 900.0 μM with a detection limit of 0.57 μM). Important-
ly, the proposed electrode was successfully applied for simultaneous de-
termination of DA, AC, FA and NAC. Also, the constructed electrode was
used for determination of DA, AC, FA and NAC in real samples.
[54] R.N. Goyal, V.K. Gupta, S. Chatterjee, Biosensors and Bioelectronics 24 (2009)
3562–3568.
[55] R.N. Goyal, V.K. Gupta, S. Chatterjee, Biosensors and Bioelectronics 24 (2009)
1649–1654.
[56] E.L. D'Antonio, E.F. Bowden, S. Franzen, Journal of Electroanalytical Chemistry 668
(2012) 37–43.
[57] R.N. Goyal, M. Oyama, V.K. Gupta, S.P. Singh, R.A. Sharma, Sensors and Actuators
B: Chemical 134 (2008) 816–821.
[58] V.K. Gupta, M.A. Khayat, A.K. Singh, M.K. Pal, Analytica Chimica Acta 634 (2009)
36–43.
[59] K.D. Wael, Q. Bashir, S.V. Vlierberghe, P. Dubruel, H.A. Heering, A. Adriaens, Bioe-
lectrochemistry 83 (2012) 15–18.
[60] R.N. Goyal, V.K. Gupta, S. Chatterjee, Talanta 76 (2008) 662–668.
[61] R.N. Goyal, V.K. Gupta, S. Chatterjee, Electrochimica Acta 53 (2008) 5354–5360.
[62] C.M. Sánchez-Sánchez, J. Souza-Garcia, E. Herrero, A. Aldaz, Journal of Electroan-
alytical Chemistry 668 (2012) 51–59.
[63] V.K. Gupta, A.K. Singh, B. Gupta, Analytica Chimica Acta 583 (2007) 340–348.
[64] V.K. Gupta, A.K. Jain, P. Kumar, S. Agarwal, G. Maheshwari, Sensors and Actuators
B: Chemical 113 (2006) 182–186.
References
[1] C.B. Jacobs, M. Jennifer Peairs, B. Jill Venton, Analytica Chimica Acta 662 (2010)
105–127.
[2] J.M. Lee, G.R. Xu, B.K. Kim, H.N. Choi, W.Y. Lee, Electroanalysis 23 (2011) 962–970.
[3] M. Najafi, L. Maleki, A.A. Rafati, Journal of Molecular Liquids 159 (2011) 226–229.
[4] H. Beitollahi, H. Karimi–Maleh, H. Khabazzadeh, Analytical Chemistry 80 (2008)
9848–9851.
[5] I. Adamenko, L. Bulavin, V. Korolovych, K. Moroz, Y. Prylutskyy, Journal of Molec-
ular Liquids 150 (2009) 1–3.
[6] H. Beitollahi, J.B. Raoof, R. Hosseinzadeh, Electroanalysis 23 (2011) 1934–1940.
[7] P. Revest, A. Longstaff, Molecular Neuroscience, Taylor & Francis, 1998.
[8] G.S. Wilson, M.A. Johnson, Chemical Reviews 108 (2008) 2462–2481.
[9] A. Bagheri Gh, Journal of Molecular Liquids 156 (2010) 141–145.
[10] H. Beitollahi, I. Sheikhshoaie, Materials Science and Engineering: C 32 (2012)
375–380.
[11] M. Pandurangachar, B.E. Kumara Swamy, B.N. Chandrashekar, O. Gilbert, B.S.
Sherigara, Journal of Molecular Liquids 158 (2011) 13–17.
[12] S.C. Fernandes, I. Cruz Vieira, R.A. Peralta, A. Neves, Electrochimica Acta 55 (2010)
7152–7157.
[65] R.N. Goyal, V.K. Gupta, A. Sangal, N. Bachheti, Electroanalysis 17 (2005) 2217–2223.
[66] R.N. Goyal, V.K. Gupta, M. Oyama, N. Bachheti, Talanta 72 (2007) 976–983.
[67] R.N. Goyal, V.K. Gupta, M. Oyama, N. Bachheti, Electrochemistry Communications
8 (2006) 65–70.
[13] S. Chitravathi, B.E. Kumara Swamy, G.P. Mamatha, B.S. Sherigara, Journal of Mo-
lecular Liquids 160 (2011) 193–199.
[14] C. Radovan, C. Cofan, D. Cinghita, Electroanalysis 20 (2008) 1346–1353.
[15] H. Beitollahi, I. Sheikhshoaie, Journal of Electroanalytical Chemistry 661 (2011)
336–342.
[16] C.X. Xu, K.J. Huang, Y. Fan, Z.W. Wu, J. Li, Journal of Molecular Liquids 165 (2012)
32–37.
[17] H. Xiong, H. Xu, L. Wang, S. Wang, Microchimica Acta 167 (2009) 129–133.
[18] M.R. Akhgar, H. Beitollahi, M. Salari, H. Karimi-Maleh, H. Zamani, Analytical
Methods 4 (2012) 259–264.
[19] Q. Wan, X. Wang, F. Yu, X. Wang, N. Yang, Journal of Applied Electrochemistry 39
(2009) 785–790.
[68] R.N. Goyal, V.K. Gupta, N. Bachheti, Analytica Chimica Acta 597 (2007) 82–89.
[69] R.N. Goyal, V.K. Gupta, M. Oyama, N. Bachheti, Electrochemistry Communications
7 (2005) 803–807.
[70] V.K. Gupta, R. Mangla, S. Agarwal, Electroanalysis 14 (2002) 1127–1132.
[71] R.N. Goyal, V.K. Gupta, N. Bachheti, R.A. Sharma, Electroanalysis 20 (2008) 757–764.
[72] A.K. Jain, V.K. Gupta, U. Khurana, L.P. Singh, Electroanalysis 9 (1997) 857–860.
[73] V.K. Gupta, R.N. Goyal, R.A. Sharma, International Journal of Electrochemical Sci-
ence 4 (2009) 156–172.
[74] V.K. Gupta, R. Jain, O. Lukram, S. Agarwal, A. Dwivedi, Talanta 83 (2011) 709–716.
[75] R.N. Goyal, V.K. Gupta, M. Oyama, N. Bachheti, Talanta 71 (2007) 1110–1117.
[76] R. Jain, V.K. Gupta, N. Jadon, K. Radhapyari, Analytical Biochemistry 407 (2010)
79–88.
[77] V.K. Gupta, M.R. Ganjali, P. Norouzi, H. Khani, A. Nayak, S. Agarwal, Critical Re-
views in Analytical Chemistry 41 (2011) 282–313.
[20] S. Wei, F. Zhao, Z. Xu, B. Zeng, Microchimica Acta 152 (2006) 285–290.
[21] H. Beitollahi, I. Sheikhshoaie, Electrochimica Acta 56 (2011) 10259–10263.
[22] B. Bali Prasad, R. Madhuri, M.P. Tiwari, P.S. Sharma, Sensors and Actuators B:
Chemical 146 (2010) 321–330.
[23] H. Beitollahi, J.B. Raoof, R. Hosseinzadeh, Analytical Sciences 27 (2011) 991–997.
[24] H. Yang, B. Lu, B. Qi, L. Guo, Journal of Electroanalytical Chemistry 660 (2011) 2–7.
[25] H. Beitollahi, J.B. Raoof, H. Karimi-Maleh, R. Hosseinzadeh, Journal of Solid State
Electrochemistry (2011), doi:10.1007/s10008-011-1578-2.
[26] M. Liu, M. Wikonkal, D.E. Brash, Carcinogenesis 20 (1999) 1869–1872.
[27] H. Beitollahi, J.B. Raoof, R. Hosseinzadeh, Talanta 85 (2011) 2128–2134.
[28] A.R. Favaro Pipi, C. Ribeiro do, Journal of Applied Electrochemistry 41 (2011)
787–793.
[78] S.K. Srivastava, V.K. Gupta, M.K. Dwivedi, S. Jain, Analytical Proceedings including
Analytical Communications 32 (1995) 21–23.
[79] A.K. Jain, V.K. Gupta, B.B. Sahoo, L.P. Singh, Analytical Proceedings including Ana-
lytical Communications 32 (1995) 99–101.
[80] W. Sun, M.X. Yang, Q. Jiang, K. Jiao, Chinese Chemical Letters 19 (2008) 1156–1158.
[81] V.K. Gupta, A.K. Jain, L.P. Singh, U. Khurana, Analytica Chimica Acta 355 (1997)
33–41.
[82] V.K. Gupta, P. Kumar, Analytica Chimica Acta 389 (1999) 205–212.
[83] V.K. Gupta, V. Nayak, A. Agarwal, S. Singhal, Barkha, Combinatorial Chemistry &
High Throughput Screening 14 (2011) 284–302.
[29] A.A. Ensafi, H. Karimi-Maleh, S. Mallakpour, M. Hatami, Sensors and Actuators B:
Chemical 155 (2011) 464–472.
[30] I. Santos da Silva, M.F. Antão Araújo, H.A. Ferreira, J. de Jesus Gomes Varela Jr.,
S.M.C. Neiva Tanaka, A. Atsushi Tanaka, L. Angnes, Talanta 83 (2011) 1701–1706.
[31] H. Karimi-Maleh, M. Keyvanfard, K. Alizad, M. Fouladgar, H. Beitollahi, A. Mokhtari, F.
Gholami-Orimi, International Journal of Electrochemical Science 6 (2011) 6141–6150.
[32] K.H. Carlsson, I. Jurna, Neuroscience Letters 77 (1987) 339–343.
[33] D. Casper, U. Yaparpalvi, N. Rempel, P. Warner, Neuroscience Letters 289 (2000)
201–204.
[84] A.K. Jain, V.K. Gupta, L.P. Singh, Analytical Proceedings including Analytical Com-
munications 32 (1995) 263–266.
[85] S.K. Srivastava, V.K. Gupta, S. Jain, Electroanalysis 8 (1996) 938–940.
[86] A.J. Bard, L.R. Faulkner, Electrochemical Methods: Fundamentals and Applica-
tions, 2nd ed. Wiley, New York, 2001.
[87] E. Laviron, Journal of Electroanalytical Chemistry 101 (1979) 19–28.
[34] J.P. Courade, F. Caussade, K. Martin, D. Besse, C. Delchambre, N. Hanoun, M. Hamon, A.
Eschalier, A. Cloarec, Naunyn-Schmiedeberg's Archives of Pharmacology 364 (2001)
534–537.