Anal. Method Environ. Chem. J. 4 (1) (2021) 16-25

Research Article, Issue 1

Analytical Methods in Environmental Chemistry Journal

Journal home page: www.amecj.com/ir

AMECJ

Development of electrochemical sensor based on carbon

paste electrode modiﬁed with ZnO nanoparticles for

determination of chlorpheniramine maleate

Hamideh Asadollahzadeh ^a,*

^aDepartment of Chemistry, Faculty of Science, Kerman branch, Islamic Azad University, Kerman, Iran, P. O. Box

7635131167, Kerman, Iran

A R T I C L E I N F O :

Received 12 Dec 2020

Revised form 3 Feb 2021

Accepted 28 Feb 2021

A B S T R A C T

Zinc oxide (ZnO) nanoparticles with an average size of 60 nm have

been successfully prepared by microwave irradiation. Carbon paste

electrode (CPE) was modiﬁed with ZnO nanoparticles and used for

the electrochemical oxidation of chlorpheniramine maleate (CPM).

Cyclic voltammetry (CV) study of the modiﬁed electrode indicated

that the oxidation potential shifted towards a lower potential by

approximately 106 mV and the peak current was enhanced by 2 fold

in comparison to the bare CPE (ZnO/CPE-CV). The electrochemical

behaviour was further described by characterization studies of scan

rate, pH and concentration of CPM. Under the optimal conditions

the peak current was proportional to CPM concentration in the

range of 8.0 ×10^-7to 1.0 × 10^-3mol L^-1with a detection limit of 5.0

× 10^-7mol L^-1by differential pulse voltammetry (DPV). The peak

current of CPM is linear in the concentration range of 0.8 - 1000

μM (R²=0.998). The ZnO/CPE has a good reproducibility and high

stability for the determination of CPM using this electrode. The

proposed method was successfully applied to the determination of

CPM in pharmaceutical samples. In addition, the important analytical

parameters were compared with other methods which show that ZnO/

CPE-CV procedure are comparable to recently reported methods.

Available online 28 Mar 2021

------------------------

Keywords:

Chlorpheniramine maleate,

Pharmaceutical determination,

Carbon paste electrode,

Cyclic voltammetry,

ZnO nanoparticles

antagonist has been used to treat allergies such

1. Introduction

as hay fever, and other respiratory tract allergies

[1]. The common side effects of chlorpheniramine

(CPM, CP) include sleepiness, restlessness, and

weakness dry mouth and wheeziness. CPM/CP is

often combined with phenylpropanolamine to form

an allergy medication with both antihistamine and

decongestant properties,CPM/CPisapartofaseriesof

antihistamines including pheniramine (Naphcon).

As previous work, the CPM/CP synthesized

through pyridine based on alkylation by

4-chlorophenylacetonitrile. The CPM generated by

alkylating with 2-dimethylaminoethylchloride in

Antihistamines are a class of drugs commonly used

to treat symptoms of allergies. These drugs help

treat conditions caused by too much histamine, a

chemical created by your body’s immune system.

Chlorpheniramine maleate [3-(4-chlorophenyl)-

N,N-dimethyl-3-pyridin-2-yl-propan-1-amine,

CPM] is an alkyl amine antihistamine. For

more than 30 years, the CPM as a H₁-receptor

*Corresponding Author: Hamideh Asadollahzadeh

Email: asadollahzadeh90@yahoo.com

https://doi.org/10.24200/amecj.v4.i01.130

CPE-ZnO nanoparticles for CPM determination

Hamideh Asadollahzadeh

17

Schema 1. Synthesis of CPM/CP based on alkylation by pyridine

the presence of sodium amide (Schema 1). Several

methods have been reported for the determination

of CPM maleate including, spectrophotometry [2],

liquid chromatography [3], liquid chromatography-

massspectrometry[4],gaschromatography[5],high

performance liquid chromatography [6]. However,

these instrumental methods have suffered some

disadvantages such as time consuming, solvent-

usage intensive and requires expensive devices

and maintenance [7]. The electrochemical methods

using chemically modiﬁed electrode have been

widely used in sensitive and selective analytical

methods for the detection of the trace amounts

of biologically important compounds. Electrode

surface may be changed with metal nanoparticles

and such surfaces have found various applications

within the sector of bio electrochemistry,

particularly in biosensors. it’s also been observed

that nanoparticles can act as conductivity centers

facilitating the transfer of electrons. Additionally,

they provide large catalytic area. Several types of

nanoparticles, including metal nanoparticles [8-

10], oxide nanoparticles [11-13], semiconductor

nanoparticles and even composite nanoparticles

[14-16] are widely utilized in electrochemical

sensors and bio sensors [17]. Some electrochemical

methods are also reported for the determination of

CPM by voltammetry [18-21]. Electrochemical

sensors satisfy many of the requirements for such

tasks particularly owing to their inherent speciﬁcity,

rapid response, sensitivity and simplicity of

preparation [18]. To our knowledge, no study has

reported the electrocatalytic oxidation of CPM by

using ZnO modiﬁed carbon paste electrode. Thus,

in the present work, the ZnO nanoparticle have been

synthesized using microwave irradiation process

and a modiﬁed carbon paste electrode is fabricated

by using ZnO nanoparticles for the determination

of CPM. All results were validated by spiking

samples and compared to other methods.

2. Experimental

2.1. Chemicals and Reagents

Pure CPM, sodium dihydrogen ortho phosphate

(NaH₂PO₄), disodium hydrogen phosphate

(Na₂HPO₄), sodium phosphate (Na₃PO₄),

orthophosphoric

acid

(H₃PO₄₎,

sodium

hydroxide (NaOH), hydrochloric acid (HCl),

Zn(NO₃)₂.4H₂O and graphite powder were

obtained from Merck. The buffer solutions were

prepared from orthophosphoric acid and its

salts in the pH range of 8 to 11. All the aqueous

solutions were prepared by using double distilled

water. High viscosity paraffin (d =0.88 kg L⁻¹)

from Merck was used as the pasting liquid for

the preparation of the carbon paste electrodes.

2.2. Apparatus

Electrochemical studies were performed using

a Metrohm polarograph potentiostat-galvanostat

(Metrohm Computrace 797-VA). The 797 VA is a

voltammetric measuring stand that is connected

to a PC. The computer software provided controls

the measurement, records the measured data and

evaluates it. Operation is most straightforward

due to the well-laid-out structure of the program.

The integrated potentiostat with galvanostat

guarantees the highest sensitivity with reduced

noise. Voltammetry system for the determination

of organic additives in electroplating baths with

Anal. Method Environ. Chem. J. 4 (1) (2021) 16-25

18

cyclic voltammetric stripping (CVS). Complete

accessories with VA Computrace software and

all electrodes for a complete measurement

system: Rotating platinum disk electrode

(RDE), Ag/AgCl reference electrode and Pt

auxiliary electrode. Three-electrode system

consisted of a bare CP and ZnO/CPE electrode

as the working electrode, Ag/AgCl (3M KCl) as

the reference electrode and a platinum wire as

the auxiliary electrode. A Metrohm 691 pH/Ion

meter was used for pH measurements. Solutions

were degassed with nitrogen for ten minutes

prior to recording of the voltammogram. X-ray

diffraction (XRD) patterns were recorded by a

Philips-X’pertpro, X-ray diffractometer using

Ni-filtered Cu Ka radiation in University of

Kashan-Iran. Scanning electron microscopy

(SEM) images were obtained from LEO

instrument model 1455VP.

long). Electrical contact was made by forcing

a copper wire down into the tube. When

necessary, a new surface was obtained by

pushing out an excess of paste and polishing

it on weighing paper. Unmodified CPE was

prepared in the same way without adding of

ZnO nanoparticles.

2.5. Procedure and sample preparation

20 pieces of CPM tablet (Daro pakhsh. Iran) were

powdered in a mortar. A portion equivalent to a stock

solution of a concentration of about 0.01 M was

accurately weighed and transferred into a 100 mL

calibrated ﬂask and completed to the volume with

double distilled water. The contents of the ﬂask were

sonicated for 10 min to affect complete dissolution.

Appropriatesolutionswerepreparedbytakingsuitable

aliquots of the clear supernatant liquid and diluting

them with the phosphate buffer solutions. Also, 0.5 ml

of an ampoule of CPM, according to its speciﬁcations,

each ml of which contains 10 mg of the drug, was

placed in a 25 ml calibrated ﬂask and completed with

a buffer at pH=10 and voltammetry was performed

on it. The differential pulse voltammograms (DPV)

were recorded between 0.4 and 1.2 V. The oxidation

peak current of CPM was measured. The parameters

for DPV were pulse width of 0.05 s, pulse increment

of 4 mV, pulse period of 0.2 s, pulse amplitude of 50

mV and scan rate of 50 mVs^-1.

2.3. Synthesis of ZnO nanoparticles

In this work, zinc acetate and graphene powders

were used as the starting reagent. 0.41 mol

of Zn(NO₃)₂.4H₂O was dissolved in 50 ml of

deionized water under vigorous stirring. 1 ml of

NaOH (1 M) was then added dropwise to the

solution. Afterward, the solution was exposed by

microwave irradiation with different powers and

times. The microwave oven followed a working

cycle of 30 s on and 70 s off (30 % power). After

reaction in microwave the samples were cooled

to room temperature naturally. Precipitates were

washed with deionized water and ethanol, and

air-dried at room temperature.

3. Results and discussion

3.1. XRD analysis

The phase type, crystal structure and purity of

the product obtained are determined by the XRD

method. The XRD pattern of the as obtained ZnO

nanoparticles as sample number 1 was shown in

Figure 1. Peaks in this pattern are reported in the

range of 2Ɵ from 20 to 80 degrees. Patterns of

the samples were indexed as a cubic phase. The

XRD results proved the high crystallinity and

purity of the products synthesized by microwave

method. According to XRD data, the crystalline

size (D_c) of ZnO nanoparticles can be determined

by using Debye- Scherrer formula. The obtained

average particle size was found to be 60 nm.

2.4. Preparation of bare carbon paste

electrode and modified carbon paste electrode

The modified carbon paste electrode was

prepared by hand mixing 0.1 g of ZnO

nanoparticles with 0.9 g graphite powder with

a mortar and pestle. Then paraffin was added

to the above mixture and mixed for 30 min

until a uniformly wetted paste was obtained.

This paste was then packed into the end

of a glass tube (ca. 3.35 mm i.d. and 10 cm

CPE-ZnO nanoparticles for CPM determination

Hamideh Asadollahzadeh

19

Fig. 1. XRD patterns of ZnO nanoparticles sample 1

3.2. Scanning electron microscopy

the nucleation of the particles is increased, and

since the particles have a very active surface,

large and cohesive masses are obtained in all test

conditions. Therefore, the sample prepared in 360

W power and 4 min time due to the creation of

nanoparticles in nanometer size according to the

scale of images and homogeneous distribution

is an optimized condition for time and power

consumption to make ZnO nanoparticles. The

produced ZnO nanoparticles have mean diameters

of approximately 40-80 nm.

In Figure 2 shows SEM image of ZnO powder

obtained at 4 min and 360 W (sample no 1), at

540 W (sample no 2) and 750 W (sample no 3). As

can be seen from SEM images, at 360 power, the

reaction is faster due to the generation of more free

radicals in solution and increased heat production

due to the rotation of these active species. The

formed nanoparticles have relatively smaller sizes

and better distribution. At 540 and 720 W, due to

the very high energy produced in these powers,

Fig. 2. SEM images of the ZnO nanoparticles for a) sample no. 1, b) sample no. 2, c) sample no. 3

Anal. Method Environ. Chem. J. 4 (1) (2021) 16-25

20

3.3. Electrochemical behavior of CPM at the

ZnO/CPE

3.4. Effect of pH

The effect of pH of the solution on the

electrochemical response of CPM was investigated

from pH 8 to 11 (although lower pH was also

examined in which the peak did not appear well).As

can be seen in the Figure 4, with increasing pH, the

anodic potential shifts to more negative potentials,

which indicates better oxidation of the material

at the electrode surface and the electrocatalytic

effect. A linear relationship existed between the

potential and pH in the range 8 to 11 (Fig. 5). The

linear regression equation was E= -60.5pH+1582

(R²=0.991). The slope of 59 mV/pH suggests that an

equal number of protons and electrons are involved

in the oxidation process. Also, with increasing pH,

the peak current increases to 10 and at pH = 11,

the current decreases, so pH = 10 is chosen as the

optimal point.

The electrochemical behavior of CPM has been

studied in two electrodes. Cyclic voltammetry

(CV) was applied to investigate the electrochemical

behavior of 0.4 mM CPM in 0.1 M phosphate buffer

at pH 10 with a bare CPE and ZnO/CPE. Figure

3 shows the cyclic voltammograms in the CPE

and ZnO/CPE electrode. As shown in this ﬁgure,

in the presence of CPM, an irreversible oxidation

peak at 1.093 V on the bare CPE attributed to the

electrochemical oxidation of CPM. In the case of the

ZnO /CPE, the oxidation peak of CPM decreased to

0.987 V and the peak current increased by 2.0 times

compared with that for the bare CPE. These results

suggestedthatZnOobviouslyacceleratetheelectron

transfer at the electrode surface and improve the

electrochemical performance accordingly.

Fig. 3. Cyclic voltammograms of CPE and ZnO/CPE at presence of 0.4 mM CPM in 0.1

phosphate buffer solution (pH 10) at scan rate 50 mVs^-1

CPE-ZnO nanoparticles for CPM determination

Hamideh Asadollahzadeh

21

Fig.4. a) Cyclic voltamogram of CPM at different pH b) Relationship between the peak potential of CPM and pH.

Fig. 5. Cyclic voltammograms of ZnO/CPE in the presence of 0.2 mM of CPM in 0.1 phosphate

buffer solution (pH 10) at different scan rates (from inner to outer): 30, 50, 70, 100, 130, 200

½

and 300 mV s^-1. Insets: b, peak current vs. square root of scan rate (v )

Anal. Method Environ. Chem. J. 4 (1) (2021) 16-25

22

3.5. Effect of scan rate

of CPM. The phosphate buffer solution of pH 10

was selected as the supporting electrolyte for the

quantiﬁcation of CPM as it gave maximum peak

current at pH 10. DPV obtained with increasing

amounts of CPM showed that the peak current

increased linearly with increasing concentration, as

shown in Figure 6. Using the optimum conditions

described previously, linear calibration curves

were obtained for CPM in the range of in range

The effect of scan rate on the electrocatalytic

oxidation of CPM at the ZnO /CPE was

investigated by cyclic voltammetry. As can be seen

in the Figure 5a, the scanning potential increases

the peak CPM oxidation shifts to more positive

potentials, which imposes a kinetic constraint on

the electrochemical reaction. Figure 5b illustrates

that a linear relationship existed between the

oxidation peak currents of CPM and the square root

(v^1/2) of the scan rate in the range from 30 to 300

mVs^-1, indicating a diffusion-controlled process.

The linear regression equation was expressed as

-7

of 8×10 to 1×10^-3M. (Fig. 6 Inset). The linear

equation I=0.159x+6.99 (R²=0.994).

3.7. The repeatability and stability of the ZnO/CPE

Repeatability of the ZnO/CPE was examined by the

determination of 0.5 mM of CPM in 0.1 M phosphate

buffer solution at pH=10 with the same electrode 5

times. A relative standard deviation (RSD) value

of 2.76% was observed, that indicating a good

reproducibility of ZnO/CPE for CPM determination.

Furthermore, the operational stability of ZnO/CPE

was investigated by CV method every 2 days in 2

weeks. Only a small decrease of current (about 3.5%)

for 2 mM CPM was observed, which can be attributed

to the good stability of the modiﬁed electrode.

I

_(μA)= 24.597v^1/2-2.942 (R²=0.991).

3.6. Calibration curve

In order to develop a voltammetric method for

determination of the drug, the DPV mode is selected,

because the peaks are sharper and better deﬁned at

lower concentration of CPM than those obtained

by cyclic voltammetry, with a lower background

current, resulting in improved resolution.

According to the obtained results, it was possible

to apply this technique to the quantitative analysis

Fig. 6. DPV obtained at a ZnO/CPE for different concentrations of CPM (0.8 to 1000 μM). Inset:

linear relationship between the peak current and concentration of CPM, scan rate: 50 mV s^-1

CPE-ZnO nanoparticles for CPM determination

Hamideh Asadollahzadeh

23

3.8. Analysis of real samples

for ampoule. Recovery studies were carried out

after the addition of known amounts of the drug

to various preanalyzed formulations of CPM.

The results are listed in Table 1. Analytical

parameters obtained here were compared with

results obtained by other methods which show

that they are comparable or better than the values

reported by other groups (Table 2).

In order to evaluate the applicability of the

proposed method in the real sample analysis, it

was used to detect CPM in tablets and ampoule

(4 mg per tablet and 10 mg/mL for ampoule)

(Fig. 7). The results are in good agreement with

the content marked in the label. The detected

content was 4.06 mg per tablet with 95%

recovery and 9.76 mg/mL with 101 %recovery

Fig.7. DPV obtained at a ZnO/CPE for standard solution 0.0001M

of CPM, tablet, ampoule and standard added with tablet sample.

Table. 1. Determination of CPM in tablet and ampoule sample with ZnO/CPE by DPV method

Amount CPM in

sample (mg)

Found in

sample

Added

(mg)

Deffected after Recovery

Sample

addition (mg)

(%)

95.62

106.3

Tablet

4

4.06±0.08

9.77±0.2

2.74

3.5

2.62±0.1

Ampoule

10

3.73±0.07

Anal. Method Environ. Chem. J. 4 (1) (2021) 16-25

24

Table 2. Comparison of analytical parameters for determination of CPM with different analytical methods.

Electrode

Method

LOD(μM)

LR(μM)

Ref

CPE-ion exchanger

CPE-SDS

PM

DPV

CV

0.51

1.7

1.2-10000

1.0 – 800

2.0 -45

[18]

[7]

Ru/Pty/GCE

0.338

[19]

MWCNT-modiﬁed GCE

CPE- CO nanostructure

CPE- ZnO Nanoparticle

DPV

1.63

0.08

0.50

5.0-500

0.1-10

[20]

[21]

0.8–1000

This work

method for simultaneous determination

of diphenhydramine, promethazine,

4. Conclusions

ZnO/CPE was successfully fabricated and has

shown electrocatalytic effect on the oxidation

of CPM. In Comparison with the bare CPE, the

presence of small amounts of ZnO reduced the

oxidation peak potential of CPM while increased

the current response of CPM. The CPM peak

current is linear from a concentration range of 0.8

μM to 1000 μM with excellent R²value of 0.998.

The detection limit of this modiﬁed electrode was

found to be 0.5 μM and a good reproducibility,

high stability was obtained for the determination

CPM using this electrode. The content of CPM

in tablet and ampoule samples was successfully

determined with ZnO/CPE, which indicated the

modiﬁed electrode is useable for the determination

of CPM concentration in real samples.

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5. Acknowledgement

guaifenisin,

The author is grateful to Islamic Azad University,

Kerman Branch, for ﬁnancial assistance of this

work.

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