A polyoxy group branched diazo dye as an alternative material for the fabrication of an electrochemical epinephrine sensor

Article abstract of DOI:10.1039/c9nj04802b

In the present study, a novel diazo dye with a polyoxy group (2{2[2(2-methoxyethoxy)ethoxy]ethoxy}-5-[(E)-(4-nitrophenyl)diazenyl]benzaldehyde (AZOTEG)) was used as a modifier to fabricate modified electrochemical platforms for epinephrine detection. For this purpose, a carbon paste electrode (CPE), which was the working electrode, was modified with AZOTEG molecules. An increase in epinephrine oxidation peak current with a negative shift in peak potentials demonstrated the electrocatalytic effect of the AZOTEG/CPE compared to the plain CPE. After the observation of this effect, experimental parameters like AZOTEG amount and pH were optimized. Then, the electrochemical mechanism was investigated by obtaining cyclic voltammograms versus scan rates. Under the optimized conditions, the analytical characteristics were examined and as a result, a wide linear range (0.1-75 μM) with a limit of detection and a limit of quantification of 0.013 μM and 0.042 μM (n = 3) were obtained. After the examination of the interference effect of uric acid, the developed sensor was successfully used for epinephrine detection in adrenaline injection samples.

Full text of DOI:10.1039/c9nj04802b

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A polyoxy group branched diazo dye as an
alternative material for the fabrication of an
electrochemical epinephrine sensor
Cite this: New J. Chem., 2019,
43, 18575
Okan Avcı, Benay Perk, Tugba O¨ ren Varol,
Yudum Tepeli Buyuksunetçi,
¨ ¨
˘
¨
O¨ zgul Hakli* and U¨lku Anik
*
¨
¨
In the present study, a novel diazo dye with a polyoxy group (2{2[2(2-methoxyethoxy)ethoxy]ethoxy}-5-
[(E)-(4-nitrophenyl)diazenyl]benzaldehyde (AZOTEG)) was used as a modifier to fabricate modified electro-
chemical platforms for epinephrine detection. For this purpose, a carbon paste electrode (CPE), which was
the working electrode, was modified with AZOTEG molecules. An increase in epinephrine oxidation peak
current with a negative shift in peak potentials demonstrated the electrocatalytic effect of the AZOTEG/CPE
compared to the plain CPE. After the observation of this effect, experimental parameters like AZOTEG
amount and pH were optimized. Then, the electrochemical mechanism was investigated by obtaining
cyclic voltammograms versus scan rates. Under the optimized conditions, the analytical characteristics
were examined and as a result, a wide linear range (0.1–75 mM) with a limit of detection and a limit
of quantification of 0.013 mM and 0.042 mM (n = 3) were obtained. After the examination of the inter-
ference effect of uric acid, the developed sensor was successfully used for epinephrine detection in
adrenaline injection samples.
Received 20th September 2019,
Accepted 3rd November 2019
DOI: 10.1039/c9nj04802b
rsc.li/njc
critical problem is the passivation of the electrode surface due to the
polymerization of epinephrine leading to coating of the electrode
1. Introduction
Epinephrine, a catecholamine neurotransmitter secreted from surface.6–10 In order to overcome these problems and achieve higher
the adrenal gland, has crucial roles in the regulation of the sensitivity, many attempts have been made based on the surface
central nervous system and glycogen metabolism. Since it is modification techniques so far. Negatively charged or electron-rich
secreted from the adrenal medulla, it is also known as adrenaline molecules have been used for electrode modification with this
and exists in biological fluids as an organic cation. Besides, purpose.5,8,10–14 Besides, a novel technique comprising centrifuga-
epinephrine is also used as an emergency health care medication. tion and voltammetric scanning in the same electrochemical cell
Its concentration in biological fluids is an indication to diagnose was also presented to obtain improved sensitivity for epinephrine
several diseases including Parkinson’s disease, thyroid hormone detection.9 Nevertheless, there is an increasing demand for alter-
deficiency, diabetes and cerebral malaises. Therefore, its sensitive native materials to fabricate effective electrochemical platforms for
and accurate quantification plays a key role in terms of pharma- sensitive and practical epinephrine detection.
cological studies and clinical research studies.1–5
Apart from its conventional usage as dyes and pigments,
Epinephrine is an electroactive molecule which can easily diazo compounds were also employed in organic semiconductor
oxidize. This feature can be utilised for epinephrine detection in devices such as thin film transistors and light emitting diodes. In
biological fluids and pharmaceutical formulations by monitoring addition, diazo dyes were utilized in photoresponsive and supra-
its oxidation signals via electrochemical methods.6,7 Even though molecular systems as well.15,16 In sensing and bio-sensing applica-
electrochemical methods offer low cost, sensitive and practical tions, diazo dyes have been chiefly used in the fabrication of optical
detection of epinephrine, there are crucial problems to be solved. sensors and chemosensors17–20 and there are limited papers about
Co-existence of several biomolecules (e.g. uric acid, dopamine and their usage in electrochemical sensors and biosensors in the
ascorbic acid) in biological matrices is the most challenging pro- literature.21–28 Diazo dyes were reported to be used in the disper-
blem which causes the observation of additional oxidation peaks at sion of graphene nanoplatelets in aqueous medium as well as a
closer potentials to the epinephrine oxidation potential. The other cross-linker and doping agent in the electropolymerization process
among these studies.21,23 In the majority of the electrochemical
studies in the literature, diazo dyes were electropolymerized for the
fabrication of modified electrodes and applied to electrochemical
˘
Mugla Sıtkı Koçman University, Faculty of Science, Chemistry Department, 48000,
˘
¨
Kotekli/Mugla, Turkey. E-mail: ozgulhakli@mu.edu.tr, ulkuanik@mu.edu.tr
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determination of several molecules such as fenitrothion, 4-nitro-
phenol and oxadiargyl.24–26 Diazo dye polymers in combination with
nanomaterials were also utilized to develop non-enzymatic glucose
and cholesterol biosensors.27,28 In the present study, a polyoxy group
attached diazo dye was directly constructed as a thin film without
electropolymerization for the fabrication of modified electro-
chemical platforms as a new approach. Electrochemical perfor-
mance of the developed sensor was examined towards epinephrine
oxidation and experimental parameters like modifier amount and
pH were optimized. Analytical characteristics of the proposed sensor
were investigated under optimized conditions and epinephrine
amount in adrenaline injection samples was determined.
2. Experimental
2.1. Instrumentation
Scheme 1 Synthesis of 2{2[2(2-methoxyethoxy)ethoxy]ethoxy}-5-[(E)-
(4-nitrophenyl)diazenyl]benzaldehyde (AZOTEG).
Voltammetric measurements were performed by using an Autolab
PGSTAT 12 potentiostat/galvanostat (Metrohm EcoChimie B.V.,
Netherlands) controlled by NOVA 1.10 software. A plain or modified
carbon paste electrode (CPE), Ag/AgCl (3 M KCl) and platinum wire
were utilized as the working, reference and counter electrodes,
respectively.
(t, 2H, –CH2–Cl), 3.48–3.40 (m, 8H, –CH2OCH2CH2OCH2–), 3.34–
3.31 (t, 2H, –CH2OCH3), 3.16 (s, 3H, –O–CH3); C7H15O3Cl.
2.3.2. Synthesis of 1-(3-formyl-4-hydroxyphenylazo)-4-nitro-
benzene. This was synthesized by following the literature.15
2.3.3. Synthesis of AZOTEG. AZOTEG was synthesized as
described in the literature.16 1-Chloro-2-[2-(2-methoxyethoxy)ethoxy]-
ethane (2.8 mmol) was added to a mixture of 1-(3-formyl-4-hydroxy-
phenylazo)-4-nitrobenzene (6.4 mmol) and K2CO3 (12.8 mmol) in
20 mL of dimethylformamide under an argon atmosphere. The
mixture was heated at 140 1C for 19 h under continuous stirring and
finally refluxed for 2 h. The resulting solution was concentrated. The
crude product was purified by column chromatography (Silica,
2.2. Reagents and chemicals
All reagents and chemicals used in the experiments were of
analytical grade. Fine powdered graphite (Merck) and mineral
oil (Sigma-Aldrich) were used for plain and modified electrode
fabrication. Dichloromethane (CH2Cl2) and methanol (CH3OH)
were purchased from Merck to prepare diazo dye solution. Citric
acid monohydrate, trisodium citrate dihydrate, trizma base (Sigma-
Aldrich), trizma hydrochloride, and uric acid (Sigma) were procured
to perform pH and interference effect studies. Epinephrine stock
solution was prepared daily from (Æ)-epinephrine hydrochloride
(Sigma). Phosphate buffer (PB, pH 7.0) containing appropriate
amounts of 0.067 M potassium dihydrogen phosphate, KH2PO4
(Merck) and 0.067 M sodium monohydrogen phosphate,
Na2HPO4 (Sigma-Aldrich) was used as a supporting electrolyte.
Double distilled water were used in the preparation of solutions.
1
CHCl3 : MeOH, 10 : 0.5). Yield: 85%. H NMR (CDCl3, d 7.26 ppm):
10.05 (1H, s); 8.39 (2H, d); 8.27 (1H, t); 8.22 (1H, t); 8.01 (2H, d); 7.14
(1H, d); 4.3 (2H, t), 3.9 (t, 2H), 3.7 (t, 2H), 3.6 (m, 4H), 3.5 (t, 2H), 3.33
(s, 3H) ppm. C20H23N3O7.
2.3. Synthesis of 2{2[2(2-methoxyethoxy)ethoxy]ethoxy}-5-[(E)-
(4-nitrophenyl)diazenyl]benzaldehyde (AZOTEG)
Synthesis of AZOTEG was carried out in three steps as shown in
Scheme 1. Each step of synthesis was explained below as also
previously described in the literature.15,16
2.3.1. Synthesis of 1-chloro-2-[2-(2-methoxyethoxy)ethoxy]-
ethane. This was synthesized by following the literature.16
Briefly, a mixture of triethylene glycol monomethyl ether
(0.52 mol), toluene (250 mL) and pyridine (45.3 mL) was heated.
At reflux temperature, thionyl chloride (0.52 mol) was added
dropwise from a dropping funnel under continuous stirring for
3 h. The mixture was refluxed for an additional 16 h and then
allowed to cool down. 20 mL of 0.3 M HCl was added to the mixture
at room temperature in a period of 15 min. Consequently, the
Fig. 1 Cyclic voltammograms recorded for (a) supporting electrolyte (0.067 M
PB, pH 7.0), (b) 50 mM epinephrine at the plain CPE, and (c) 50 mM epinephrine at
the AZOTEG/CPE at a scan rate of 50 mV sÀ1 with a step potential of 0.00244 V
upper organic layer was removed. The product was obtained as a
1
light yellow oil. Yield: 70%. H NMR (CDCl3; d, ppm): 3.55–3.51 and interval time of 0.048800 s (AZOTEG amount: 10 mL).
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2.4. Fabrication of AZOTEG/CPE and the electrochemical
procedure
3. Results and discussion
3.1. Electrochemical performances of the plain CPE and
Since CPE was used as a support and also a plain electrode as AZOTEG/CPE towards epinephrine oxidation
well, a homogeneous mixture of graphite and mineral oil in
The electrochemical performance of the AZOTEG/CPE was inves-
70 : 30 mass ratio was prepared at first. The obtained carbon
paste was placed in the electrode cavity and the electrode
surface was smoothened on weighing paper. In order to modify
the CPE surface, 1 mg of AZOTEG was dissolved in 1 mL of
CH2Cl2–CH3OH mixture (1 : 1 by volume). 10 mL of AZOTEG
solution was spread onto the CPE surface and left at room
temperature for 1 h for the evaporation of the solvent mixture.
The epinephrine stock solution was diluted to the required
concentration with supporting electrolyte in a 10 mL electrochemical
cell and dissolved oxygen was deaerated via nitrogen flow during a
period of 3 min. Cyclic and differential pulse voltammograms were
recorded by scanning the potential between À0.4 and +0.8 V.
tigated by recording cyclic voltammograms in the presence of
50 mM epinephrine (0.067 M PB, pH 7.0) and compared with
the plain CPE (Fig. 1). As demonstrated in Fig. 1, an oxidation
peak was observed for the CPE with an anodic peak current
2.5. Sample preparation
Adrenaline injection samples containing 1 mg mLÀ1 epinephrine
were diluted 10-fold with 0.067 M PB (pH 7.0) prior to the
voltammetric measurement.
Fig. 2 (A) Cyclic voltammograms of (a) supporting electrolyte (0.067 M
PB, pH 7.0) and 50 mM epinephrine obtained at the AZOTEG/CPE modified
with different amounts of AZOTEG (b–g: 0, 5, 20, 30, 15, 10 mL) at a scan
rate of 50 mV sÀ1 with a step potential of 0.00244 V and an interval time of
0.048800 s. (B) Plot of the epinephrine peak current–AZOTEG amount
relationship.
Fig. 3 (A) Cyclic voltammograms of 50 mM epinephrine at different pH
values (a–e: 5.0, 6.0, 7.0, 8.0, 9.0) at a scan rate of 50 mV sÀ1 with a step
potential of 0.00244 V and an interval time of 0.048800 s, (B) plot of the
epinephrine peak current–pH and (C) plot of epinephrine peak potential–
pH relationship (AZOTEG amount: 10 mL).
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of 4.510 mA at 0.237 V. In the case of AZOTEG/CPE, an
Thus, 10 mL was selected as the optimum amount of
epinephrine oxidation peak was obtained at 0.198 V with a AZOTEG for the modification and used for further experiments.
peak current of 6.334 mA. Under the same conditions, a 1.4-fold 3.2.2. Effect of pH. Working medium pH is another important
increase in the peak current with a cathodic shift of 39 mV parameter to estimate the electrochemical reaction mechanism. In
confirmed the electrocatalytic effect of the AZOTEG/CPE general, electrochemical oxidation or reduction of many organic
towards epinephrine oxidation. Since epinephrine (pKa = 8.8) molecules includes protons. Thus, pH remarkably affects the peak
is in cationic form at neutral and physiological pH, it may be currents and peak potentials of organic molecules in electro-
predicted that positively charged epinephrine may have chemical reactions.8,14 Within this purpose, the effect of pH
been attracted by an electron-rich polyoxy group of AZOTEG. on epinephrine oxidation at the AZOTEG/CPE was investigated
Besides, hydroxyl groups in epinephrine are capable of forming between pH 5.0–9.0. It is clearly seen in Fig. 3A and B that the
hydrogen bonds with oxygen atoms in the AZOTEG structure. peak current values increases with increasing pH and reaches a
Therefore, the facilitated epinephrine oxidation with increased maximum at pH 7.0 confirming that protons catalyse the
peak current may be attributed to the interaction between epinephrine oxidation reaction at the AZOTEG/CPE surface.
AZOTEG and epinephrine.8,11,29
Furthermore, it may also be inferred that the interaction
between epinephrine and the polyoxy group of AZOTEG was
predominantly maintained at pH 7.0.
3.2. Optimization of experimental parameters
3.2.1. Effect of AZOTEG amount. Modifier amount on the
On the other hand, a cathodic shift in the peak potentials
electrode surface is a crucial parameter for the fabrication of an was observed with increasing pH indicating that protons
efficient electrochemical sensor since thickness of the modifier are involved in the electrochemical oxidation reaction at the
layer directly affects the conductivity of the system.6,10,30 There- AZOTEG/CPE (Fig. 3A). In Fig. 3C, the relationship between pH
fore, AZOTEG amount was changed in the range of 0–30 mL and and peak potentials was found to be linear with a slope value of
voltammetric responses of 50 mM epinephrine (0.067 M PB, À0.071 V per pH closer to the theoretical slope value of 0.059 V
pH 7.0) were measured at a scan rate of 50 mV sÀ1 (Fig. 2). As per pH in the Nernst equation. The obtained data demon-
can be seen from the figure, the epinephrine oxidation peak strated that equal numbers of protons and electrons are
current increases up to 10 mL by increasing the amounts of involved in the electrochemical oxidation reaction of epinephrine
AZOTEG on the CPE surface, whereas larger amounts of at the AZOTEG/CPE surface, which is in accordance with pre-
AZOTEG lead to a decrease in peak current values.
viously reported studies.1,8,10,11,14
Fig. 4 (A) Cyclic voltammograms of 50 mM epinephrine (0.067 M PB, pH 7.0) at different scan rates (a–g: 10, 20, 40, 50, 100, 250, 350 mV sÀ1) with a step
potential of 0.00244 V and an interval time of 0.048800, (B) plot of epinephrine peak current–square root of scan rate, (C) plot of epinephrine peak
current–scan rate relationship, and (D) log I vs. log n plot (AZOTEG amount: 10 mL).
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3.2.3. Effect of scan rate. Effect of scan rate on epinephrine predominant than adsorption in the reaction mechanism at
oxidation was examined by varying the scan rate between the AZOTEG/CPE.31–34
10–350 mV sÀ1 to gain further knowledge about the reaction
3.3. Analytical characteristics
mechanism on the AZOTEG/CPE. In Fig. 4A, cyclic voltammo-
grams of 50 mM epinephrine (0.067 M PB, pH 7.0) at different
scan rates are shown. As can be clearly seen from Fig. 4A, while
the epinephrine oxidation peak current values gradually
increases, an anodic shift is observed in the peak potentials.
Moreover, the relationship between peak current and scan rate
was investigated and it was observed that the peak current
values linearly increased with the square root of scan rate
suggesting a diffusion-controlled process between 10–350 mV sÀ1
(Fig. 4B and C). In order to estimate the prevailing process
on the electrode surface, logarithm of peak current (log I)
versus logarithm of scan rate (log n) plot was depicted with
a slope value of 0.6511 (Fig. 4D). In theory, a slope value
of 0.5 indicates a diffusion-controlled process, whereas a
slope value of 1.0 addresses an adsorption-controlled process.
The obtained slope value indicates that diffusion is more
After the optimization of the experimental parameters, analytical
characteristics of the AZOTEG/CPE were examined. For this
purpose, the epinephrine concentration was changed in the range
of 0.1–75 mM (0.067 M PB, pH 7.0) to depict the calibration graph
in Fig. 5. Sensitivity of the sensor was evaluated in terms of limit
of detection (LOD) and limit of quantification (LOQ) values. LOD
and LOQ were calculated based on the equations of 3s/m and
10s/m (s: standard deviation of blank solution and m: slope of
calibration graph) and found as 0.013 mM and 0.042 mM (n = 3),
respectively. Relative standard deviation (RSD) was also calcu-
lated for 50 mM to estimate the repeatability and found as
4.34% (n = 3). The linear range and LOD obtained for the
AZOTEG/CPE were compared with similar studies in the litera-
ture (Table 1). As presented in Table 1, a wide linear range with
a lower LOD value were obtained for the AZOTEG/CPE com-
pared to similar studies in the literature.
3.4. Voltammetric response of epinephrine at the AZOTEG/
CPE in the presence of uric acid
Uric acid is a naturally found biomolecule in biological fluids
with epinephrine and it is a major problem for electrochemical
epinephrine detection since its oxidation peak potential is close
to the epinephrine oxidation peak potential.37,38 In order to
evaluate the selectivity of the AZOTEG/CPE, the voltammetric
responses of 10 mM epinephrine (0.067 M PB, pH 7.0) were
examined in the presence of 20 mM and 40 mM uric acid (Fig. 6).
A uric acid oxidation peak was not obtained separately at the
AZOTEG/CPE and peak shouldering around 0.4 V was attributed
Table 1 Comparison of the fabricated sensor with similar studies for
electrochemical epinephrine detection
Linear range
(mM)
LOD
(mM)
Electrode
Ref.
NiFe2O4–MWCNTs–GCEa
GCE–MWCNT/Fe3O4/
29H,31H-Pcb
0.1–1000
7.5–48
0.09
4.6
1
3
GCE/Chit-fCNTc
EDDPT/GO/CPEd
P(L-Asp)/ERGO/GCEe
ZnO–GO/SPEf
0.05–10
1.5–600
0.1–110
0.5–500
0.08–900
0.1–75
0.003
0.65
0.025
0.07
0.01
0.013
4
5
10
35
36
Present
study
CPE/NiO/CNTsg
AZOTEG/CPE
a
NiFe2O4–MWCNTs–GCE: nickel ferrite magnetic nanoparticles decorated
multiwall carbon nanotubes modified glassy carbon electrode. b GCE-
MWCNT/Fe3O4/29H,31H-Pc: multiwall carbon nanotube/iron oxide nano-
particles/29H,31H-phthalocyanine hybrid modified glassy carbon electrode.
c
GCE/Chit-fCNT: functionalized multiwall carbon nanotube-chitosan bio-
polymer nanocomposite modified glassy carbon electrode. d EDDPT/GO/
CPE: 2-(5-ethyl-2,4-dihydroxyphenyl)-5,7-dimethyl-4H-pyrido[2,3-d][1,3]thia-
zine-4-one/graphene oxide modified carbon paste electrode. e P(L-Asp)/
ERGO/GCE: poly(L-aspartic acid)/electrochemically reduced graphene oxide
Fig. 5 (A) Differential pulse voltammograms for various concentrations
of epinephrine (a: background, b–j: 0.1, 0.5, 1, 5, 10, 15, 25, 50, 75 mM).
Inset: Differential pulse voltammograms of lower concentrations of
epinephrine (a: background, b–d: 0.1, 0.5, 1 mM) in 0.067 M PB, pH 7.0
and (B) calibration plot in the range of 0.1–75 mM (modulation amplitude:
0.025 V, step potential: 0.00500 V, modulation time: 0.05000 s, interval
time: 0.5000 s).
f
modified glassy carbon electrode. ZnO–GO/SPE: zinc oxide nanorod–gra-
phene oxide nanocomposite modified graphite screen printed electrode.
CPE/NiO/CNTs: nickel oxide/carbon nanotubes nanocomposite modified
carbon paste electrode.
g
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Conflicts of interest
The authors declare that they have no conflict of interest.
References
1 A. A. Ensafi, F. Saeid, B. Rezaei and A. R. Allafchian, Anal.
Methods, 2014, 6, 6885.
2 H. Devnani, S. P. Satsangee and R. Jain, Ionics, 2016, 22, 943.
3 N. G. Mphuthi, A. S. Adekunle and E. E. Ebenso, Sci. Rep.,
2016, 6, 26938.
4 K. K. Reddy, M. Satyanarayana, K. G. Goud, K. V. Gobi and
H. Kim, Mater. Sci. Eng., C, 2017, 79, 93.
5 M. D. Tezerjani, A. Benvidi, A. D. Firouzabadi, M. Mazloum-
Ardakani and A. Akbari, Measurement, 2017, 101, 183.
6 R. N. Goyal and S. Bishnoi, Electrochim. Acta, 2011, 56, 2717.
7 T. Cho and J. Wang, Electroanalysis, 2018, 30, 1028.
8 P. Pradhan, R. J. Mascarenhas, T. Thomas, I. N. N. Namboothiri,
O. J. D’Souza and Z. Mekhalif, J. Electroanal. Chem., 2014,
732, 30.
Fig. 6 Differential pulse voltammograms recorded for 10 mM epinephrine,
10 mM epinephrine + 20 mM uric acid and 10 mM epinephrine + 40 mM uric
acid (0.067 M PB, pH 7.0) under optimum conditions.
¨
9 D. Bal Altuntas, T. Oren and U. Anik, Anal. Methods, 2016,
8, 6872.
10 B. Mekassa, M. Tessema, B. S. Chandravanshi, P. G. L. Baker
and F. N. Muya, J. Electroanal. Chem., 2017, 807, 145.
11 T. Thomas, R. J. Mascarenhas, O. J. D’Souza, S. Detriche,
Z. Mekhalif and P. Martis, Talanta, 2014, 125, 352.
12 J. Li, X. Wang, H. Duan, Y. Wang and C. Luo, Mater. Sci.
Eng., C, 2016, 64, 391.
to uric acid oxidation.37 In spite of shouldering peaks of uric acid,
it was observed that the peak currents of 10 mM epinephrine were
changed as À1.25% and À4.87% in the presence of 20 mM and
40 mM uric acid, respectively. In addition, the epinephrine oxida-
tion potentials were not shifted due to the presence of uric acid
indicating that the voltammetric responses of epinephrine were
not significantly affected.
13 A. C. Anithaa, K. Asokan and C. Sekar, Electrochim. Acta,
2017, 237, 44.
14 J. Tashkhourian, S. F. Nami-Ana and M. Shamsipur, J. Mol.
Liq., 2018, 266, 548.
3.5. Epinephrine detection in adrenaline injection samples
˙
15 H. Dinçalp, F. Toker, I. Durucasu, N. Avcıbas-ı and S. Icli,
The applicability of the developed sensor was evaluated by
detecting the epinephrine amount in adrenaline injection
samples under the optimized conditions. The recovery value
was calculated as 98.7 Æ 2.4% (n = 3). It was indicated that the
AZOTEG/CPE exhibited satisfactory results for epinephrine
detection in real samples.
Dyes Pigm., 2007, 75, 11.
16 O. Birel, N. Kavasoglu, A. S. Kavasoglu, H. Dincalp and
B. Metin, Phys. B, 2013, 412, 64.
17 S.-Y. Na and H.-J. Kim, Tetrahedron Lett., 2015, 56, 493–495.
18 M. Sonawane, K. Tayade, S. K. Sahoo, C. P. Sawant and
A. Kuwar, J. Coord. Chem., 2016, 69, 2785.
19 N. Koonrugsa and S. Fuangswasdi, Spectrochim. Acta, Part A,
2019, 215, 15.
4. Conclusion
20 H. Zhang, A. Hou, K. Xie and A. Gao, Sens. Actuators, B, 2019,
286, 362.
In this study, a polyoxy group containing diazo dye modified
electrochemical sensor was fabricated for practical and sensi- 21 N. G. Yasri, A. K. Sundramoorthy and S. Gunasekaran, RSC
tive epinephrine detection. It was observed that the electro- Adv., 2015, 5, 87295.
chemical response of epinephrine at the AZOTEG/CPE was 22 M. Taei, F. Hasanpour, S. Habibollahi and L. Shahidi,
improved as attributed to the interaction between epinephrine J. Electroanal. Chem., 2017, 789, 140.
and polyoxy groups in the AZOTEG structure. Under the opti- 23 M. Wang, M. Cui, W. Liu and X. Liu, J. Electroanal. Chem.,
mized conditions, the AZOTEG/CPE exhibited enhanced sensi- 2019, 832, 174.
tivity with a wide linear range compared to previously reported 24 O. Surucu, G. Bolat and S. Abaci, Talanta, 2017, 168, 113.
studies in the literature. The utility of the AZOTEG/CPE in 25 K. Giribabu, Y. Haldorai, M. Rethinasabapathy, S.-C. Jang,
practical applications was tested for epinephrine detection in
adrenaline injection samples. The obtained results showed that
R. Suresh, W.-S. Cho, Y.-K. Han, C. Roh, Y. S. Huh and
V. Narayanan, Curr. Appl. Phys., 2017, 17, 1114.
diazo dyes with various functional groups may be alternatively 26 M. Saber-Tehrani, A. Pourhabib, S. W. Husain and
used in sensor and biosensor fabrication to determine biologi-
cally important molecules unlike their conventional usage.
M. Arvand, Electroanalysis, 2012, 24, 2395.
27 O. Surucu and S. Abaci, Mater. Sci. Eng., C, 2017, 78, 539.
18580 | New J. Chem., 2019, 43, 18575--18581 This journal is ©The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2019

View Article Online
NJC
Paper
¨
˘
28 P. K. Bairagi and N. Verma, J. Electroanal. Chem., 2018, 34 T. Dogan, U. Anik and Z. Dursun, ChemistrySelect, 2019,
814, 134.
4, 7704.
¨
¨
¨
29 T. Oren, O. Birel and U. Anık, Anal. Lett., 2018, 51, 1680.
35 M. Baniasadi, S. Jahani, H. Maaref and R. Alizadeh, Anal.
Bioanal. Electrochem., 2017, 9, 718.
¨
¨
30 T. Oren Varol and U. Anik, New J. Chem., 2019, 43, 13437.
31 S. J. Malode, J. C. Abbar, N. P. Shetti and S. T. Nandibewoor, 36 V. K. Gupta, H. Mahmoody, F. Karimi, S. Agarwal and
Electrochim. Acta, 2012, 60, 95. M. Abbasghorbani, Int. J. Electrochem. Sci., 2017, 12, 248.
32 S. L. Zorluoglu, I. H. Tas-demir, A. Ece and E. Kiliç, Can. 37 E. Wierzbicka and G. D. Sulka, Sens. Actuators, B, 2016,
J. Chem., 2013, 91, 951. 222, 270.
33 H. M. Rageh, M. M. Abou-Krisha, A. M. Abo-bakr and 38 A. Wong, T. A. Silva and O. Fatibello-Filho, Electroanalysis,
M. Abd-Elsabour, Int. J. Electrochem. Sci., 2015, 10, 4105. 2017, 29, 2491.
˙
˘
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