Bimetallic cobalt-iron diselenide nanorod modified glassy carbon electrode: an electrochemical sensing platform for the selective detection of isoniazid

Article abstract of DOI:10.1039/d1ra01572a

The increasing demand of a sensitive and portable electrochemical sensing platform in pharmaceutical analysis has developed widespread interest in preparing electrode materials possessing remarkable properties for the electrochemical determination of target drug analytes. Herein, we report the synthesis, characterization and application of bimetallic cobalt-iron diselenide (FeCoSe₂) nanorods as electrode modifiers for the selective detection of a commonly used anti-tuberculosis drug Isoniazid (INZ). We prepared FeCoSe₂nanorods by a simple hydrothermal route and characterized these by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and temperature-programmed reduction (TPR) techniques. The electrochemical characterization of FeCoSe₂modified GCE was performed by cyclic voltammetry (CV) and square wave anodic stripping voltammetry (SWASV). Under optimized experimental conditions, a linear current-concentration response was obtained for INZ in the range of 0.03-1.0 μM, with very low limit of detection 1.24 × 10^?10M. The real applicability of the designed FeCoSe₂/GCE sensing platform was adjudicated by the detection of INZ in biological samples.

Full text of DOI:10.1039/d1ra01572a

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PAPER
Bimetallic cobalt–iron diselenide nanorod
modified glassy carbon electrode: an
electrochemical sensing platform for the selective
detection of isoniazid†
Cite this: RSC Adv., 2021, 11, 12649
a
Sundas Sultan,a Muhammad Zulqarnain,a Afzal Shah,
Naveeda Firdous,a
*
Jan Nisar, b Muhammad Naeem Ashiq,c Esraa M. Bakhshd and Sher Bahadar Khand
The increasing demand of a sensitive and portable electrochemical sensing platform in pharmaceutical
analysis has developed widespread interest in preparing electrode materials possessing remarkable
properties for the electrochemical determination of target drug analytes. Herein, we report the synthesis,
characterization and application of bimetallic cobalt-iron diselenide (FeCoSe2) nanorods as electrode
modifiers for the selective detection of a commonly used anti-tuberculosis drug Isoniazid (INZ). We
prepared FeCoSe2 nanorods by a simple hydrothermal route and characterized these by X-ray diffraction
(XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive
X-ray spectroscopy (EDX) and temperature-programmed reduction (TPR) techniques. The
electrochemical characterization of FeCoSe2 modified GCE was performed by cyclic voltammetry (CV)
and square wave anodic stripping voltammetry (SWASV). Under optimized experimental conditions,
a linear current-concentration response was obtained for INZ in the range of 0.03–1.0 mM, with very low
limit of detection 1.24 ꢀ 10ꢁ10 M. The real applicability of the designed FeCoSe2/GCE sensing platform
was adjudicated by the detection of INZ in biological samples.
Received 27th February 2021
Accepted 24th March 2021
DOI: 10.1039/d1ra01572a
rsc.li/rsc-advances
techniques have their own advantages but every technique has
some limitations. Therefore, efforts are underway to search for
Introduction
effective tools on case to case basis. Electrochemical techniques
are attracting attention owing to their peculiar features of being
cheaper, easy to operate, portable, sensitive and selective. Many
research teams have employed modied electrodes for INZ
detection.10–15 But the modied electrodes suffer from serious
fouling effects that can be minimized by the right selection of
supporting electrolyte and type of material used for electrode
modication.16–19
Isoniazid (INZ) chemically named as pyridine-4-carboxylic acid
hydrazide is the most commonly used anti-tuberculosis drug.1
Tuberculosis is an infectious bacterial disease caused by
Mycobacterium tuberculosis (MBT) and INZ has a great potency to
suppress the activity of MBT.2 In this regard, it is highly
important to monitor the INZ level in biological uid to control
and regulate the level of this drug for effective treatment.3,4 The
chemical structure of INZ is shown in Fig. 1.
A variety of analytical approaches such as high-performance
liquid
chromatography,
Raman
spectroscopy,
chem-
iluminescence, colorimetry, capillary electrophoresis, uorim-
etry,
chemometry,
titrimetry,
polarography,
and
spectrophotometry are used for INZ analysis.5–9 All these
aDepartment of Chemistry, Quaid-i-Azam University, Islamabad, 45320, Pakistan.
E-mail: afzals_qau@yahoo.com
bNational Centre of Excellence in Physical Chemistry, University of Peshawar,
Peshawar, 25120, Pakistan
cInstitute of Chemical Sciences, Bahauddin Zakaryia University, Multan 6100,
Pakistan
dDepartment of Chemistry, King Abdulaziz University, P. O. Box 80203, Jeddah 21589,
Saudi Arabia
† Electronic supplementary information (ESI) available. See DOI:
10.1039/d1ra01572a
Fig. 1 Chemical structure of isoniazid (INZ).
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Metal chalcogenides and specically metal diselenides oxidation/reduction reactions using cobalt diselenide, whereas
(MSe2) have attained great attention for ongoing research.20–22 electrochemical studies using composite materials of cobalt
The higher metallic character of Se in chalcogenides might diselenide are rather limited.
attributed to their extraordinary physical and electrochemical
Herein, we report FeCoSe2 nanorods modied GCE for
properties. In recent years, various metal selenides MSe2 (M ¼ electrochemical detection of INZ in neutral media. Our objec-
Co, Fe, Mo, Cu, and Ni) have been extensively applied as effec- tive is to use comparatively cheaper electrode modier for more
tive electrocatalysts in electrochemical applications.23–26 Among sensitive detection of INZ. The morphological features of metal
various metal diselenides, FeSe2 and CoSe2 have been mostly nanorods provide excellent electrochemical sensing platforms
investigated due to their excellent electrical conductivity, low due to high surface area and higher exposure of specic crystal
diffusion length for ion/electron, high specic capacitance, facets. To the best of our knowledge, no previous work is re-
mechanical stability, low charge transfer resistance, and ported on the use of FeCoSe2/GCE for the electroanalytical
signicant recycling ability.27–30 In fact, 3d electrons with a low detection of INZ. To get a robust electroanalytical signal for INZ
spin in Co metal facilitate the metallic characteristic of CoSe2 on the FeCoSe2/GCE, we have optimized experimental condi-
which leads to increase in the charge transfer during the elec- tions. We have validated the real-world applicability of FeCoSe2/
trocatalytic process. The electrocatalytic activity of CoFeSe2 alloy GCE in the real samples.
could be enhanced due to the synergistic effect between Fe and
CoSe2. The hetero-metallic bond formation in bimetallic alloys
results in the tuning of the bonding patterns of catalyst surface
with the reactant molecules (INZ).31 The strong metal–metal
Experimental section
Chemicals and apparatus
interactions in bimetallic systems also modify the electrical and
mechanical properties which make them favorable for different
electrocatalytic applications.
Isoniazid (C6H7N3O, Merck, $ 99%), iron(II) chloride tetrahy-
drate (FeCl2$4H2O, Merck, $ 99%), cobalt(II) chloride hexahy-
drate (CoCl2$6H2O, Merck, 98%), sodium hydroxide (NaOH,
Cobalt diselenide nanobelts graed on carbon ber presented Merck, $ 97%), EDTA (C10H14N2Na2O8$2H2O, Merck, 99%),
a robust electrochemical performance that can be correlated to boric acid (H3BO3, Merck, $ 99.5%), and phosphoric acid
the synergistic effect between CoSe2 and carbon ber besides 3D (H3PO4, Merck, $ 99%) were purchased and used as received
cathode architecture providing catalytic stability.32 Liu et al.
without any purication. The Britton Robinson buffer (BRB) of
successfully fabricated 3D Ni(1ꢁx)CoxSe2 mesoporous nanosheet
on Ni foam with tunable stoichiometry.33 The collective effects of
special morphological design and electronic structure engi-
neering enable the integrated highest catalytic activity and
outstanding stability in a wide pH range. Recently, Zheng et al.,
studied phase transition of CoSe2 from cubic to orthorhombic
with appropriate doping of phosphorus.34 The striking electro-
catalytic performance can be attributed to the favorable elec-
tronic structure and local coordination environment created by
this doping-induced structural phase transition strategy. In
literature, most of the studies are focused on electrochemical
pH 7 was used as supporting electrolyte which was prepared by
mixing 0.04 M H3BO3, 0.04 M H3PO4, and 0.04 M CH3COOH.
The pH of BRB was adjusted to 7 by adding 0.2 M NaOH solu-
tion. All the solutions were made in doubly distilled water.
Instrumentation
XRD analysis was performed on Rigaku D/max 2500 with
ꢀ
a radiation source Cu Ka1 (l ¼ 1.54056 A). SEM and TEM
images of the prepared samples were recorded on electron
microscope JEM 2100 (USA) equipped with EDS unit for chem-
ical analysis. The accelerating voltage was kept at 10 kV and 100
Fig. 2 Schematic representation of the synthesis of CoFeSe2 modification.
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kV for SEM and TEM images, respectively. TPR analysis of the conditioning was done in consecutive 20 runs in the respec-
synthesized nanocomposite was performed on ChemiSorb 2750 tive potential window to reduce signal to noise ratio.
(Micromeritics-USA) to evaluate the different metallic phases
and alloying effects of constituent metals. The surface area
Results and discussion
XRD analysis
analysis was performed using Sorptometer Kelvin 1042 (Costech
Instruments) at liquid N2 temperature (ꢁ196 ꢂC) aer degassing
ꢂ
the samples at 200 C for 2 h.
Fig. 3 illustrates the XRD pattern of the synthesized FeCoSe2
bimetallic nanocatalyst. The sharp and intense peaks of XRD show
that the synthesized material has high crystallinity. The diffraction
peaks at 2q ꢃ30.71ꢂ, 34.37ꢂ, 35.8ꢂ, 47.8ꢂ, 50.41ꢂ, 53.33ꢂ, and 55.3ꢂ
in the XRD spectra of FeCoSe2 correspond to (101), (110), (120),
(211), (002), (031), and (131) hkl planes, respectively (Powder
Diffraction Standard Database: JCPDS # 21-0432).
Catalyst preparation
At rst, CoSe2 was synthesized by following the hydrothermal
route as shown in Fig. 2. The solution labeled as A was prepared by
mixing 0.8 mmol of CoCl2$6H2O with 2 mL of 0.5 M ethylene
diamine tetra-acetic acid (EDTA). Another solution labeled as B
was prepared by mixing 0.162 mmol of Se powder in 8 mL of 3.3 M
NaOH. Both solutions A and B were then mixed via ultra-
sonication. Aer that, the resultant mixture was shied to auto-
Surface area analysis
To assess the surface properties such as the specic surface area
and pore particularity, CoFeSe2 nanocomposite was further
explored by N2 adsorption–desorption isotherms as shown in
Fig. 4. A typical type IV isotherm (Fig. 4A) with H3 hysteresis
loop between 0.4 and 0.8 P/Po reveals the mesoporous nature of
the material as per IUPAC classication.35 The BET surface area
of CoFeSe2 nanocatalyst was found to be 93.14 m2 gꢁ1. The
specic surface area is highly inuenced by the surface
morphologies and internal porous structures. Besides, the pore
size distribution curve (Fig. 4B) was derived from the desorption
isotherm by applying the Barret–Joyner–Halenda (BJH) method.
Narrow scattering of pores was obtained with the maximum
distribution of pores with a size of 5.5 nm, reecting a unimodal
behavior. The large value of the BET area and distinct meso-
porous nature contributed towards introducing more active
sites which were later manifested by optimum electrochemical
sensing of isoniazid over the electrode surface modied with
this synthesized catalyst.
ꢂ
clave and kept at 180 C for 18 h for the hydrothermal reaction.
Similarly, FeCoSe2 bimetallic catalyst was prepared by adding
0.4 mmol of FeCl2$4H2O to the above mentioned solution A. In
each case, the black product was collected and washed with
deionized water followed by air drying. The total quantity of metal
sources (Fe + Co) was kept very low and constant (0.8 mmol).
Finally, feeding ratios of metals was further conrmed by EDX.
Electrode fabrication
Before each electrochemical analysis, GCE was polished using
alumina powder (0.05 mm) and carefully washed in an ultrasonic
bath with doubly distilled water, followed by a mixture of acetone
and nitric acid (1 : 1) mixture, and nally washed by doubly
distilled water and dried in a desiccator. The 1 mg of FeCoSe2 was
dispersed in 1 mL of isopropanol via ultrasonication for 30
minutes to achieve uniform dispersion. Then, 5 mL of FeCoSe2
solution was drop casted over the polished surface of bare GCE
(0.07 cm2). The fabricated electrode was rst dried at room
temperature for 20 minutes and then completely dried in the oven
at 50 ꢂC for 30 minutes. The FeCoSe2/GCE was then employed for
electrochemical analysis of INZ under optimized conditions.
Morphological characterizations
SEM images of FeCoSe2 (Fig. 5(A–C)) indicate the presence of
FeCoSe2 nanorods with the diameter ranging from 40 to 90 nm
which is suitable for electrochemical applications. It displayed
the uniform distribution of FeCoSe2 nanorods with no
agglomeration high metal dispersion of this optimal catalyst
Electrochemical characterization
Cyclic voltammetry and SWASV measurements were performed
at room temperature on potentiostat Gamry interface 1000. The
three electrode setup was used for electrochemical studies. Ag/
AgCl (3 M KCl), a platinum wire and modied GCE were used as
reference, counter and working electrodes respectively.
Measurement of pH of solutions was done using INOLAB pH
meter. The INZ concentration was quantied by assessing
oxidation peak current values using the SWASV technique.
SWAS voltammograms were recorded under optimized condi-
tions (i.e., deposition voltage of 0.0 V and deposition time of 90 s
by using both pure GCE and modied FeCoSe2/GCE electrodes.
For voltammetric investigations experimental conditions were
optimized by varying: scan rate, volume of catalyst suspension
for electrode fabrication, pH, and buffer solution. These opti-
mizations were done and the best current response was ob-
tained in a medium of pH 7 using catalyst suspension of 5 mL for
electrode modication. Prior to each measurement, pre- Fig. 3 XRD pattern of the synthesized FeCoSe2 bimetallic catalyst.
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Fig. 4 (A) N2 adsorption–desorption isotherm and (B) pore size distribution curve of CoFeSe2 nanorods using BJH method.
resulted to a better catalytic activity for hydrazine electro- depicted the distribution of Co, Fe, and Se metals with the
oxidation, later on. Furthermore, the TEM image (Fig. 5D) uniform dispersion.
ensures the presence of rod type structures in the synthesized
material with an average size of 40 nm.
Fig. 7 presents TPR proles of the prepared nanocomposite.
In general, two step reduction of cobalt oxide (Co3O4) occurs as
follows:36
Co3O4 + H2 / 3CoO + H2O
3CoO + 3H2 / 3Co0 + 3H2O
(1)
(2)
EDX analysis
EDX analysis was performed at randomly selected points over
the surface of the prepared samples (Fig. S1†). Fig. 6A shows the
EDX spectra of CoFeSe2 with resultant sharp peaks of Co, Fe,
and Se elements. The considerable quantitative weight
percentage was recorded for Co, Fe, and Se elements of about
TPR analysis
19.26%, 1.21%, and 59.91%, respectively. The co-existence of TPR prole of monometallic Co catalyst showed the 3 reduction
Co, Fe, and Se presented the synergistic effect to form metal peaks in the range of 150–800 ꢂC, respectively. The appearance
alloy NPs. Moreover, EDX mapping (Fig. 6B–E) of CoFeSe2 of these reduction peaks can be attributed to the reduction of
Fig. 5 (A–C) SEM micrographs at various magnifications and (D) TEM image of synthesized FeCoSe2 nanorods.
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Fig. 6 (A) EDX profile for chemical composition and (B–E) EDX mapping for elemental distribution of the prepared CoFeSe2 nanocomposite.
Co3O4 to CoO and further reduction of CoO to metallic Coo.37 In There were observed sharp peaks with a narrow peak potential
comparison, the CoSe2 catalyst presented ease in reduction difference and an obvious enhancement in the oxidation-
behavior than that of the monometallic Co sample. In the case reduction peak currents in the CV of FeCoSe2/GCE compared
of CoFeSe2, the incorporation of Fe metal even in a small to bare GCE, signifying rapid electron transfer process.38
content led to a decline in the reduction temperature of cobalt
The active surface area of the electrodes was estimated
oxide and reduction peaks were shied towards lower temper- according to the Randles–Sevcik equation: ipa ¼ 2.69 ꢀ 105n3/
ature region. In this aspect, the present study suggested that the 2AD1/2v1/2 C, where A is the active surface area (cm2), ipa is the
alloying effect of the constituent metals (Co, Fe, and Se) may redox peak current of potassium ferricyanide, n is the number
promote the catalytic efficiency of CoFeSe2/GCE towards elec- of electrons transferred (2 in this case), D is the diffusiꢁo1n
trosensing of INZ. Overall, the synergistic effect might be coefficient (0.76 ꢀ 10ꢁ5 cm2 sꢁ1, 25 ꢂC), v is the scan rate (V s
)
accountable for the development in the eld of catalysis.
and C is the concentration of analyte (5 mM). The calculated
active surface area of bare GCE and modied electrode are
found to be 0.071 cm2 and 0.117 cm2, respectively. The larger
active surface area is obtained for the modied electrode shows
the greater electrochemical activity of the FeCoSe2/GCE as
compare to bare GCE.
Active surface area measurements
Voltammetric investigations of the FeCoSe2/GCE were per-
formed using 5 mM potassium ferrocyanide (K3[Fe(CN)6]/
K4[Fe(CN)6]) solution as a redox probe. Fig. S2† shows the cyclic
voltammograms recorded by using bare and modied GCE.
Electrooxidation of INZ at FeCoSe2/GCE modied electrode
The electrocatalytic oxidation of Isoniazid was evaluated by
SWASV technique. Fig. 8A shows the square wave voltammo-
grams for the oxidation of INZ at bare and FeCoSe2/GCE in the
BRB solution of pH 7. At a potential of 0.45 V, an oxidation
signal for INZ was obtained by SWASV. The current response for
INZ oxidation at FeCoSe2/GCE is manifestly promoted as
compared to bare GCE. This enhancement in the current signal
by using FeCoSe2/GCE is attributed to the larger active surface
area, good conductivity, and excellent electrosensing potency of
the FeCoSe2 nanorods. Fig. 8B shows the schematic presenta-
tion for electrochemical oxidation mechanism of INZ over
modied FeCoSe2/GCE.39 These outcomes veried that the
projected FeCoSe2/GCE is efficiently accomplished for the vol-
tammetric sensing of INZ.
Optimization of experimental parameters
The pH of the medium has a pronounced effect on INZ detec-
tion and was observed using FeCoSe2/GCE by changing the pH
of the solution from 4 to 8 as shown in Fig. 9A. It was seen that
Fig. 7 TPR profiles of the synthesized nanocatalysts.
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solution, signifying the direct involvement of the proton in
electrode processes. Also, the slope value 52.48 mV per unit pH
was obtained from the plot of Ep vs. pH (Fig. 9B) which
demonstrates that the oxidation of INZ involves equal no of
electrons and protons.
The effect of changing accumulation potential (ꢁ0.4 to 0.3)
on the oxidation peak current of INZ was studied by SWASV as
shown in Fig. S3A.† The oxidation peak current magnitude
increases gradually towards positive potential direction until it
reached its maximum value at 0.0 V thereaer, it decreased
abruptly. So, an accumulation potential of 0.0 V was selected as
optimum potential. The effect of accumulation time was also
studied as shown in Fig. S3B.† It showed the enhancement in
the peak current value up to 90 s, aerward the current value
declines with increasing time, and hence accumulation time of
90 s was selected for further experimental work.
Under optimized conditions calibration plot for INZ was ach-
ieved by SWASV in the concentration range of 0.03–1 mM as shown
in Fig. 10A. The results obtained showed a direct relation to the
oxidation peak current against INZ concentration. The limit of
detection (LOD) and limit of quantication (LOQ) for INZ detec-
tion were calculated by using eqn (3) and eqn (4), respectively
LOD ¼ 3s/m
LOQ ¼ 10s/m
(3)
(4)
Here, “s” is the standard deviation of the peak current of blank
solution (three runs) and “m” denotes the slope of current versus
concentration plot.40
Fig. 8 (A) SWASV of (a) bare GCE in 25 mM solution of INZ, (b)
FeCoSe2/GCE in 25 mM solution of INZ solution, and (c) FeCoSe2/GCE
in solvent (BRB of pH 7) containing no INZ at a scan rate of 50 mV sꢁ1
,
Fig. 10B presents the effect of INZ concentration on its peak
accumulation potential of 0.0 V, and accumulation time of the 90 s, current response at the modied FeCoSe2/GCE. From the linear
and (B) electrochemical oxidation mechanism of INZ over modified
FeCoSe2/GCE.
relationship of the peak current and INZ concentration the LOD and
LOQ with values of 1.24 ꢀ 10ꢁ10 M and 4.14 ꢀ 10ꢁ10 M were eval-
uated respectively. The regression data and various other parame-
the peak current value increases steadily with increasing the pH
of the solution up to pH 7 and then a steady fall in current
response was recognized by further increasing pH of the solu-
tion. Hence, pH 7 was optimized for further experimental work.
Furthermore, a shi in peak potential for oxidation of INZ was
observed in the negative direction with an increase in pH of the
ters obtained from calibration curves are presented in Table S1.†
Stability and reproducibility of fabricated GCE
To check the precision of the proposed method, repeatability
and reproducibility of the fabricated GCE was investigated.
Fig. 9 (A) SWASV of 16 mM solution of INZ using FeCoSe2/GCE in 4–8 pH range and (B) Plots of Ep and Ip vs. pH.
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Fig. 10 (A) SWAS voltammograms of INZ in the concentration range of 0.03–1 mM at FeCoSe2/GCE in BRB solution (pH 7) under optimized
conditions (scan rate of 50 mV sꢁ1, accumulation potential of 0.0 V, and accumulation time of 90 s and (B) the plot of Ipa versus concentration.
The intra-day precision of the FeCoSe2/GCE was checked by interference experiments were performed as shown in Fig. S5.†
performing three repeated measurements within a day and the It was observed that 500 folds' excess of Ca2+, NH4+, Mg2+,
% RSD was found to be 2.22%. The stability based on inter-day glucose, 200 folds of ascorbic acid and uric acid, showed almost
precision was checked by performing three repeated no interference to anodic peak current response of INZ (RSD ¼
measurements between days by SWASV technique and the % 1.59%). The interference experiment showed that the fabricated
RSD was found to be 0.56%. The relative standard deviation (% GCE has the ability of anti-jamming. The comparison of this
RSD) was calculated for isoniazid detection and found to be in work with reported modied electrodes for INZ detection is
acceptable range i.e., less than 5% as shown in Fig. S4.† The summarized in Table 1.
results achieved specify that the FeCoSe2/GCE have good
precision, thus can be employed for sensitive and selective
detection of INZ.
Practical application of FeCoSe2/GCE for INZ analysis
To check the practical applicability of the FeCoSe2/GCE, the
analyte INZ was assessed in physiological uids i.e., in human
serum and urine samples by applying SWASV technique.
Interference study
In order to study the interference of various interferences, Detection of drugs in physiological uids can help in following
which commonly exist in the biological samples, some their metabolic fate. The biological uids were originally taken
Table 1 Comparison of analytical parameters of our modified FeCoSe2/GCE electrode with reported ones for the determination of isoniazid
using various techniques
Linear range
Electrodes
Technique
(mM)
Medium
LOD
Ref.
GC/Ag–P(MMA-co-AMPS)ESP
GO/PAG modied GCE
Cu/GO/GCE
SPCE/PH electrode
MWCPE
PdNPs/CILE
ERGO/GCE
RGO–Au/GCE
CoTRP(dcbpy)2]-Ni/GO
FeCoSe2/GCE
Amperometry
Differential pulse voltammetry (DPV)
Amperometry
Differential pulse voltammetry (DPV)
Differential pulse voltammetry (DPV)
Cyclic voltammetry (CV)
LSV
DPV
BIA
0.05–150
20–1400
0.1–500
0.5–110
1–1000
5–100
0.1 M PBS (pH 7)
PBS (pH 7)
10 nM
11
12
13
14
15
16
17
18
2.59 mM
23.4 nM
17 mM
0.5 mM
0.47 mM
0.17 mM
0.01 mM
3.5 mM
0.12 nM
Phosphate buffer (pH 7)
Phosphate buffer (pH 7)
Acetate buffer (pH 4)
Phosphate buffer (pH 7)
Phosphate buffer (pH 7)
Phosphate buffer (pH 7)
KNO3 (pH 7)
2–70
0.1–1000
100–1000
0.03–1
19
SWASV
BRB (pH 7)
This work
Table 2 INZ determination in real samples (urine and human serum) by proposed SWASV technique
INZ conc. detected
Recovery
RSD (%)
Sample
Analyte
INZ conc. added (mM)
(mM)
(%)
(n ¼ 3)
Urine
Human serum
INZ
INZ
5
2
4.94
1.96
98.8
98.0
2.5
3.4
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from a healthy volunteer. Each biological sample was diluted up
to 15 times by using BRB of pH 7 and then spiked by INZ under
commonly used standard addition methods. Each sample was
analyzed three times (n ¼ 3) to check the reproducibility. The
recovery results obtained for spiked INZ samples by using
FeCoSe2/GCE showed a very low RSD value of 2.5% and 3.4% for
urine and human serum samples, respectively. This outcome
validated that the FeCoSe2/GCE has its specic extensive reli-
ability towards detection of INZ in biological uids. The nd-
ings of the real sample analyses are listed in Table 2.
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Conclusions
In the present work FeCoSe2 modied GCE was successfully
fabricated and used for electrochemical determination of
isoniazid. The FeCoSe2/GCE showed gures of merit in the
context of wider linear range, lower limit of detection and
strong resilience to interfering agents. Owning to the excep-
tional properties of FeCoSe2, it offers an enhanced oxidation
response of INZ in neutral medium. The higher sensitivity and
lower detection limit are attributed to good conductivity, larger
surface area, excellent catalytic properties and amplication
effect of FeCoSe2 nanorods. The FeCoSe2/GCE also displayed
great potential application for INZ detection in human serum
and urine samples with acceptable recoveries. The robust
performance of FeCoSe2/GCE bimetallic catalysts would be
correlated to the synergistic effect of constituent metals, crys-
tallinity, unique morphology (nanorods), uniform dispersion of
alloy particles, narrow pore size distribution, and presence of
more active sites as ensured by XRD, SEM, TEM, EDX, and TPR
analyses.
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isoniazid,
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for the Simultaneous In Vitro Spectrophotometric Analysis of
Rifampicin and Isoniazid from Modied-Release Anti-TB
Drug Delivery Systems, Curr. Drug Delivery, 2010, 7, 5.
7 P. R. Chellini, T. O. Mendes, P. H. Franco, B. L. Porto,
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V. K. Tippavajhala, I. C. Cesar, M. A. Oliveira and
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Ethical statement
This article does not contain any direct studies on human
participants and animals. The experiments were performed in
compliance with the relevant laws and institutional guidelines
of Quaid-i-Azam University, Islamabad, with prior approval
from the ethical committee. Only the assay corresponding to
practical testing of the designed sensor includes the use of
urine and human serum. The urine sample was obtained with
informed consent of the healthy donor and according to insti-
tutional guidelines. While the drug free synthetic human serum
was purchased from Sigma Aldrich.
´
8 M. A. Lomillo, R. O. Domınguez and M.
́ Mj. Arcos,
Resolution of ternary mixtures of rifampicin, isoniazid and
pyrazinamide by differential pulse polarography and
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square-wave adsorptive stripping voltammetric estimation
in bulk form, tablets and biological uids at a mercury
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arginine-modied electrode for the simultaneous
Conflicts of interest
There are no conicts to declare.
Acknowledgements
Authors are highly thankful to Quaid-i-Azam University and
Higher Education Commission of Pakistan for providing the
research facility. Authors gratefully acknowledge the Deanship
of Scientic Research (DSR), King Abdulaziz University, Jeddah,
Saudi Arabia for supporting this work under grant no. (KEP-1-
130-41).
12656 | RSC Adv., 2021, 11, 12649–12657
© 2021 The Author(s). Published by the Royal Society of Chemistry

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RSC Adv., 2021, 11, 12649–12657 | 12657