Ultrasensitive electrochemical detection of methyl parathion pesticide based on cationic water-soluble pillar[5]arene and reduced graphene nanocomposite

Article abstract of DOI:10.1039/C8RA08555B

We report a rapid, sensitive and selective electrochemical sensor based on pillar[5]arene (CP5) reduced graphene (rGO) nanohybrid-modified glassy carbon electrode CP5-rGO/GCE for the trace detection of methyl parathion (MP) by differential pulse voltammetry (DPV) for the first time. Compared to beta-cyclodextrin (β-CD)-functionalized reduced graphene (rGO)-modified GCE β-CD-rGO/GCE, the proposed CP5-rGO/GCE sensor exhibits excellent electrochemical catalytic activity, rapid response, high sensitivity, good reproducibility and anti-interference ability towards MP. The recognition mechanism of β-CD/MP and CP5/MP was studied by ¹H NMR. The results indicate a higher supramolecular recognition capability between CP5 and MP compared to that between β-CD and MP. The β-CD-rGO and CP5-rGO nano-composites were prepared via a wet chemistry approach. The resulting nano-composites have been characterized by thermogravimetric analysis (TGA), fourier transform infrared spectrometry (FTIR), charge transfer resistance (R_ct) and zeta potential. The CP5-rGO/GCE combines the merits of CP5 and rGO, and is used for quantitative detection of MP. It has a low detection limit of 0.0003 μM (S/N = 3) and a linear response range of 0.001-150 μM for MP. This method has been used to detect MP in soil and waste water samples with satisfactory results. This study provides a promising electrochemical sensing platform and is a promising tool for the rapid, facile and sensitive analysis of MP.

Full text of DOI:10.1039/C8RA08555B

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PAPER
Ultrasensitive electrochemical detection of methyl
parathion pesticide based on cationic water-
soluble pillar[5]arene and reduced graphene
nanocomposite†
Cite this: RSC Adv., 2019, 9, 345
Xiaoping Tan, * Yan Liu, Tingying Zhang, Shasha Luo, Xi Liu, Hexiang Tian,
Yang Yang and Chunlian Chen
We report a rapid, sensitive and selective electrochemical sensor based on pillar[5]arene (CP5) reduced
graphene (rGO) nanohybrid-modified glassy carbon electrode CP5-rGO/GCE for the trace detection of
methyl parathion (MP) by differential pulse voltammetry (DPV) for the first time. Compared to beta-
cyclodextrin (b-CD)-functionalized reduced graphene (rGO)-modified GCE b-CD-rGO/GCE, the
proposed CP5-rGO/GCE sensor exhibits excellent electrochemical catalytic activity, rapid response, high
sensitivity, good reproducibility and anti-interference ability towards MP. The recognition mechanism of
1
b-CD/MP and CP5/MP was studied by H NMR. The results indicate a higher supramolecular recognition
capability between CP5 and MP compared to that between b-CD and MP. The b-CD-rGO and CP5-rGO
nano-composites were prepared via a wet chemistry approach. The resulting nano-composites have
been characterized by thermogravimetric analysis (TGA), fourier transform infrared spectrometry (FTIR),
charge transfer resistance (Rct) and zeta potential. The CP5-rGO/GCE combines the merits of CP5 and
rGO, and is used for quantitative detection of MP. It has a low detection limit of 0.0003 mM (S/N ¼ 3)
and a linear response range of 0.001–150 mM for MP. This method has been used to detect MP in soil
and waste water samples with satisfactory results. This study provides a promising electrochemical
sensing platform and is a promising tool for the rapid, facile and sensitive analysis of MP.
Received 16th October 2018
Accepted 10th December 2018
DOI: 10.1039/c8ra08555b
rsc.li/rsc-advances
For example, Tonle et al. prepared a Gemini surfactant-
intercalated clay-modied electrode for the determination of
Introduction
ꢁ7
ꢁ6
21
Organophosphorus pesticides (OPs) have high toxicity, which MP with a linear dynamic range of 4.0 ꢀ 10 to 1.0 ꢀ 10 M.
1
,2
oen lead to difficulty breathing and death. The broad use of Xu et al. employed a poly (malachite green)/graphene nanosheet–
OPs for pest control has caused serious concerns in regards to Naon (PMG/GNs–NF) composite lm modied glassy carbon
ꢁ8
3
,4
human health, food safety and environmental protection.
Methyl parathion (MP) is a common OP used in sh hatcheries 10 M and a detection limit of 2 ꢀ 10 M. Dai et al. used
electrode to detect MP with a linear range of 2 ꢀ 10 to 1.5 ꢀ
ꢁ6 ꢁ9
22
5,6
and agriculture. It is potentially toxic and may be harmful to Naon as an additive, and drop-casted ZrO
human health. Therefore, the rapid and sensitive determi- carbon electrode (ZrO
-CNFs onto a glassy
-CNF/GCE). The modied electrode was
2
2
7,8
ꢁ9
9
–11
nation of MP is increasingly important.
determined by gas chromatography-mass spectrometry,
MP is currently then applied to detect MP with a linear range of 1 ꢀ 10 to 2 ꢀ
ꢁ8 ꢁ10
23
12
10 M and a detection limit of 3.4 ꢀ 10
M. Although these
13
14
immunoassays,
chromatography-mass spectrometry and mass spectrometry.
However, these methods oen need complicated sample and sensitive to detect MP remain an unmet need.
molecular
imprinting,
liquid electroanalytical methods were rapid and sensitive, some of them
1
5,16
exhibited poor selectivity. Therefore, tools that are both selective
pretreatments or suffer from high costs. Electroanalytical
Macrocyclic arenes play an important role in the eld of
24–27
methods are simple, rapid and cheap, and have been used for supramolecular chemistry.
They contain aromatic rings linked
17–20
the determination of MP and other pesticides.
by methylenes or heteroatoms, such as oxygen, nitrogen and
28
sulfur. Conventional macrocyclic arenes, such as cyclodextrins,
calixarenes, calixpyrroles, resorcinarenes and cyclotriveratrylenes,
with different electronic constitutions and topological structures,
Key Lab of Inorganic Special Functional Materials, Chongqing Municipal Education
Commission, School of Chemistry and Chemical Engineering, Yangtze Normal
University, Fuling, 408100, China. E-mail: xptan@yznu.cn
29,30
exhibit a variety of host–guest properties.
Cyclodextrins (CDs)
†
Electronic supplementary information (ESI) available: Experimental procedures are toroidal in shape with a hydrophilic exterior and a hydrophobic
of synthesis and characterization of CP5, other materials and apparatus. See DOI:
inner cavity. These interesting characteristics enable them to
1
0.1039/c8ra08555b
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4
8
selectively bind various guest molecules and form stable host/ graphene and amphiphilic pillar[5]arene-gold nanoparticles.
31,32
guest complexes in their hydrophobic cavity.
Pillar[n]arenes were rst reported by Ogoshi et al. in 2008.
Zhao et al. reported a competitive uorescence sensing for
acetaminophen. Therefore, the composites of pillar[n]arene
33
49
Pillar[n]arenes are composed of p-hydroquinone units held and graphene demonstrate some special performances.
together by methylene bridges linking the para-positions of the Herein, we describe a rapid and sensitive electrochemical
p-hydroquinone units in cyclic arrays. Currently, pillar[n]arenes sensor based on cationic pillar[5]arene (CP5)-reduced graphene
are recognized as important players in supramolecular chem- (rGO) nanohybrid material-modied glassy carbon electrode
istry due to their easy synthesis, versatile functionality, unique (CP5-rGO/GCE). This material was successfully fabricated for the
pillar shaped structure, excellent host–guest properties and trace determination of MP by DPV for the rst time. Compared to
inarticial supramolecular assembly characteristics, and this beta-cyclodextrin-functionalized reduced graphene composite (b-
has resulted in numerous electrochemical and biomedical CD-RGO), the electrochemical sensor has higher electrical signal
34–38
material applications.
and recognition capability. This is due to the higher recognition
In 2015, Li et al. rst reported a novel coumarin-pillar[5] of CP5 compared to that of b-CD towards MP. The electro-
arene (P5C10) as a selective uorescent probe for MP, however chemical sensing platform based on CP5-rGO/GCE is illustrated
it suffered from limited selectivity and sensitivity. Thus, they in Fig. 1. This method is simple, highly sensitive and selective,
constructed an electrochemical sensor based on pillar[5]arene and has been successfully applied to MP detection in soil and tap
39
for the determination of MP. The use of a water-soluble water samples. The proposed approach can also be extended to
macrocyclic host that interacts with graphene via p–p stack- other potential applications in environmental, industrial, and
ing and hydrogen bonding interactions can improve selectivity biological samples, such as drug metabolites in organisms.
40–44
and sensitivity.
Graphene has unique mechanical, thermal,
and electronic properties as well as a high surface area, low cost,
45,46
Materials and methods
It has
and low toxicity arising from its strict 2D structure.
many applications in sensors, drug carriers and other techno- Chemicals and materials
logical elds. Mao et al. reported a sensor for detecting paraquat
b-Cyclodextrin (b-CD, >99%) and graphene oxide (GO) were
obtained from Shanghai TITAN Tech Co., Ltd. (Shanghai,
China). Cationic water-soluble pillar[5]arene (CP5) was
4
7
in living cells based on pillar[5]arene and graphene. Zhou et al.
reported an electrochemical sensing platform based on reduced
Fig. 1 The corresponding cartoon representations of MP, CP5 and b-CD and the illustration of CP5-rGO (A) and b-CD-rGO (B) nanohybrids-
based electrochemical sensing method towards methyl parathion.
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Scheme 1 The synthesis of cationic water-soluble pillar[5]arene CP5.
synthesized via the previously published procedures and the Electrochemical impedance spectroscopy (EIS) was recorded in
ꢁ
1
5
synthetic route is shown in Scheme 1 with synthetic details the frequency range of 10 to 10 Hz with an amplitude of 5 mV
3
ꢁ/4ꢁ
described in the ESI.† Other chemicals utilized were of analyt- employing [Fe(CN)6]
(2.0 mM) redox couple (1 : 1) with KCl
ical grade and were used without further purication. All of the (0.1 M) as the supporting electrolyte. All of the electrochemical
aqueous solutions were prepared via deionized water (DW, 18 measurements were carried out at room temperature.
MU cm). The apparatus and other reagents are shown in the SI.
The structure and purity of all compounds were conrmed by
1
13
H NMR and C NMR (see Fig. S1–S8†).
Results and discussion
Characterization of the b-CD-rGO and CP5-rGO composites
Synthesis of CP5-rGO and b-CD-rGO composites
GO and CP5-rGO were characterized by the UV-vis spectroscopy
and the results are shown in Fig. S9.† The absorption peak of
graphene oxide dispersion at 230 nm gradually redshis to
CP5 (20 mg) and GO (20 mg) were dissolved in deionized water
(50 mg). Ammonia (3 mL) and ascorbic acid (200 mg) were then
added, and the reaction mixture was stirred for 20 h at room
temperature. Aer the reaction was completed, the CP5-rGO
composite was obtained aer being centrifuged at 12 000 rpm
for 40 min and was washed 4 times. The CP5-rGO powder was
obtained by freeze drying for further characterization. The
preparation of the b-CD-rGO composite was similar to that of
the CP5-rGO composite.
2
60 nm, which indicates that the reduction process between
graphene oxide and reduced graphene successfully proceeds
under the alkaline conditions. We further characterized the
microstructure of CP5-rGO by TEM (Fig. 2A). The TEM image
reveals that CP5-rGO material is randomly aggregated thin,
wrinkled sheets closely associated with each other. As shown in
Fig. 2B, the AFM morphology of CP5-rGO is a nano-sheet
structure, indicating the single-layer feature of graphene. It
was difficult to distinguish the CP5 molecules in the TEM
image, and thus PP5-rGO composite was further characterized
by FTIR spectroscopy, zeta potential measurements, TGA and
XPS analysis.
Fabrication of the modied electrodes
A glassy carbon electrode (GCE, 3 mm in diameter) was
sequentially polished with Al O powder (0.3 and 0.05 mm) and
2 3
then sonicated in ethanol and DW to remove the physically
adsorbed substances and dried in air. The CP5-rGO nanohybrid
Electrochemical characterization of the modied electrodes
used a value of charge transfer resistance (Rct) with a potential
of 0.1 V. The frequency ranges are 10 to 10 Hz using 2.0 mM
ꢁ1
material was dissolved in DW at a concentration of 0.5 mg mL
with ultrasonic treatment for 20 min. This resulted in a homo-
ꢁ
1
5
3
ꢁ/4ꢁ
ꢁ
1
[Fe(CN)
6
]
redox couple (1 : 1) with 0.1 M KCl as the sup-
geneous suspension. b-CD-rGO (0.5 mg mL ) or rGO homo-
geneous suspensions were also similarly obtained. To prepare
the CP5-rGO-modied electrode, 5 mL of the CP5-rGO suspen-
sion was dropped onto the electrode surface and dried in air.
The resulting electrode was termed as CP5-rGO/GCE. b-CD-rGO/
GCE and rGO/GCE were also prepared via the similar procedure.
50
porting electrolyte. The value of the electron-transfer resis-
tance (R ) of the modied electrode is estimated by the
ct
semicircle diameter. Fig. 3A illustrates the EIS of the bare GCE,
rGO/GCE, CP5-rGO/GCE and b-CD-rGO/GCE. Evidently, the bare
GCE exhibits a semicircle portion, and the value of Rct is esti-
mated to be 900 U. The rGO/GCE is estimated to be 750 U,
which attributes to high conductivity of rGO. When the CP5-
rGO and b-CD-rGO modied the bare GCE, the semicircles
Electrochemical measurements
Cyclic voltammetry (CV) was achieved in phosphate buffer were increased to 1500 U and 2100 U, respectively. This is
0.1 M pH 6.0) containing 20 mM of MP. Differential pulse vol- caused by the organic macromolecules of CP5 and b-CD
(
tammetry (DPV) was realized in phosphate buffer (0.1 M pH 6.0) hindering the electron transfer. This renders the interfacial
from 0.4 to ꢁ0.4 V with a pulse amplitude of 0.05 V and a pulse charge transfer difficult. The results show that b-CD and CP5
width of 0.05 s containing different concentrations of MP. molecules are successfully immobilized on the surface of rGO.
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Fig. 2 TEM (A) and AFM (B) of CP5-rGO nano-material.
The Rct value of b-CD-rGO/GCE is higher than that of CP5-rGO/ potential of b-CD-rGO decreases by approximately 20 mV
GCE indicating that the electrical conductivity of b-CD is worse because of the negative charge on the b-CD. Generally, the zeta
than CP5 due to the quaternary ammonium bromide of CP5.
potentials of b-CD-rGO and CP5-rGO are higher than 30 mV
Fourier transform infrared spectroscopy (FTIR) results of the suggesting that b-CD-rGO and CP5-rGO dispersions are colloi-
b-CD-rGO and CP5-rGO composites are observed in Fig. 3B. dally stable. The zeta potential of rGO is ꢁ23.3 mV (lower than
Fig. 3B shows no signicant absorption in the FTIR spectrum of 30 mV), indicating the poor aqueous dispersion of rGO. These
the reduced graphene (rGO) indicating that the reduction effect results are in accordance with the photographs of r-GO, b-CD-
is very good. The characteristic absorption peak of b-CD appears rGO and CP5-rGO aqueous dispersions, as shown in Fig. S10.†
in the FTIR spectrum of the b-CD-rGO composite. The stretch-
As shown in Fig. 3E, X-ray photoelectron spectroscopy (XPS)
ꢁ1
ing vibration of C–O is 1053 cm and the asymmetric stretch- analysis is used to conrm the electronic structure and
ꢁ
1
ing vibration of –COC– is 1152 cm . The stretching vibration compositions of rGO and CP5-rGO. Fig. 3E shows a signicant N
ꢁ1
corresponding to the O–H group appears at 3386 cm . The 1s peak for the resulting CP5-rGO attributed to the CP5; no N
presence of these characteristic peaks indicates that the signal is detected on the rGO lm, which further indicates the
composite b-CD-rGO has been successfully prepared. Similarly, successful chemical modication of CP5 on rGO. Therefore,
the characteristic absorption peak of CP5 can be observed in the these results suggest that the CP5 or b-CD has been successfully
FTIR spectrum of the composite CP5-rGO. The most signicant graed on the surface of rGO.
characteristic peak on CP5 is the vibration absorption bands of
ꢁ
1
ꢁ1
ꢁ1
the benzene ring at 1612 cm , 1493 cm and 1405 cm
.
Optimization of experimental conditions for the detection of
MP at CP5-rGO/GCE
These peaks show that CP5 has been successfully compounded
by rGO.
The resulting b-CD-rGO, CP5-rGO and the other related
materials are also characterized by thermogravimetry (TGA) as
The electrochemical control experiments are performed to
optimize MP detection. The accumulation time has signicant
effects on the performance of the sensor. The pH value of PBS
buffer, accumulation potential and accumulation time were
studied for their effects on the DPV peak currents of 10 mM MP
at the CP5-rGO modied electrode in 0.1 M PBS.
The pH of the PBS buffer is a key factor underlying the
electrochemical signal of the MP. It is performed for different
pH values (4 to 8) with 10 mM MP at the CP5-rGO/GCE
shown in Fig. 3C. The pristine rGO has a minor loss in mass
ꢂ
(
18%) at about 600 C because of the pyrolysis of a very small
amount of the labile oxygen-containing functional groups. The
b-CD-rGO composite shows an abrupt mass loss when the
ꢂ
temperature is approximately 270 C due to the decomposition
of b-CD; the mass loss reached about 44 wt% when the
ꢂ
temperature is 600 C. Meanwhile, the CP5-rGO composite also
ꢂ
exhibits an abrupt mass loss at about 270 C due to the
(Fig. S11(A)†). The peak current gradually enhances with
decomposition of CP5; the mass loss reached about 46 wt%
when the temperature is approximately 600 C, indicating that
the b-CD-rGO and CP5-rGO nanohybrids are successfully
fabricated.
increasing the pH and reaches a maximum value at pH 6.0. This
may be due to the degradation of OP compounds and the
ꢂ
+
51
reduced process of MP under H condition. Fig. S11(B)† shows
that the corresponding DPV peak current value gradually
enhances with increasing the accumulation potential and rea-
ches a maximum value at ꢁ0.1 V, which suggests that the
reduction of MP at CP5-rGO/GCE is maximized. As shown in
Fig. S11(C),† the DPV peak current value reaches a maximum at
The average zeta potentials of rGO, b-CD-rGO and CP5-rGO
are ꢁ23.3, ꢁ44.1 and 34.4 mV, respectively, as shown in
Fig. 3D. Compared to the zeta potential of rGO, the zeta
potential of CP5-rGO increases by approximately 57.7 mV, and
3
+
this is ascribed to the positive charge of –N(C
2
H
5
)
3
in the CP5.
150 s of accumulation time, indicating that the reduction of MP
However, compared to the zeta potential of rGO, the zeta
at CP5-rGO/GCE is saturated. Therefore, 0.1 M pH 6.0 PBS,
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3ꢁ/4ꢁ
Fig. 3 The EIS characterization of GCE, b-CD-rGO/GCE and CP5-rGO/GCE via [Fe(CN)
6
]
(2.0 mM) redox couple (1 : 1) with KCl (0.1 M) as
supporting electrolyte (A). FTIR spectra of b-CD, b-CD-rGO, rGO, CP5-rGO and CP5 (B). TGA curves of rGO, CP5-rGO and b-CD-rGO (C). Zeta
potentials of rGO, b-CD-rGO and CP5-rGO (D). XPS survey spectra of rGO and CP5-rGO (E).
ꢁ
0.1 V accumulation potential, and 170 s accumulation time enhanced at rGO/GCE. This enhancement indicates that the high
are used for the following experiments.
surface area and high conductivity of the rGO promotes the
effective electrode area and increases the catalytic activity
towards MP oxidation and reduction. With respect to b-CD-rGO/
GCE, the redox currents of MP are improved in comparison with
rGO-modied GCE indicating that the b-CD molecules with
Electrochemical behavior of MP in different modied
electrodes
The electrochemical behavior of MP has been investigated using excellent supramolecular recognition capability form inclusion
a variety of modied electrodes. The standard MP was diluted to complexes with MP. However, the redox current increases
50 mM as a stock solution in PBS (0.1 M, pH 6.0) buffer solution, remarkably when the CP5-rGO nanohybrid is immobilized onto
and the modied electrode GCE, rGO/GCE, b-CD-rGO/GCE and the surface of a GCE. This might be because the CP5 molecules
CP5-rGO/GCE are measured for CV in a 20 mM MP solution have a large cavity, and the cavity has stronger supramolecular
(Fig. 4A). Fig. 4A shows that the bare GCE has two weak reduction recognition capability than b-CD.
peaks. Compared to the bare GCE, the peak current value of MP is
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Fig. 4 The CV curves obtained for the redox reaction of 20 mM MP in PBS (0.1 M, pH 6.0) at bare GCE, rGO/GCE, b-CD-rGO/GCE and CP5-rGO/
GCE (A). DPV curves obtained for the reduction of MP at CP5-rGO/GCE for different concentrations (B). Calibration plots of the reduction peak
current at CP5-rGO/GCE versus concentration of MP under optimal conditions (C). Selectivity studies with different species in the developed MP
detection strategy use DPV and keep all of the parameters constant. The MP concentration is 20 mM against the concentration of all of the other
substances—this is held at 1.0 mM (D).
1
The H NMR spectra of the host-guest complexation between around ꢁ0.1 V. This pair of reversible redox peaks is ascribed to
CP5 and MP, and b-CD and MP are investigated in DMSO-d to a two-electron transfer redox process.
6
illustrate the recognition mechanism of b-CD/MP and CP5/MP.
As shown in Fig. 5, the signals of the protons (Ha and Hb) of MP
have signicantly shied upeld, and the protons (H1) from
CP5 have signicantly shied downeld. These indicated host-
guest complexation by the hydrophobic interactions, p–p
interactions and decient-rich electron interactions between
Analytical performance, selectivity and real sample analysis
The analytical performance was examined with DPV measure-
ments to study potential applications of the CP5-rGO-modied
GCE. Fig. 4B shows the DPV curves of MP on CP5-rGO/GCE.
The peak current increases with the increasing MP concentra-
tions. The corresponding calibration curves for MP can also be
obtained (Fig. 4C). This method can achieve a low detection limit
of 0.0003 mM (S/N ¼ 3) and a linear response range of 0.001–150
mM. The corresponding regression equations are I (mA) ¼ 8.027C
39,51–54
CP5 and MP.
However, the proton signals (Ha and Hb) of
MP did not shi. The hydroxyl protons of b-CD shied slightly
downeld (Fig. 6). This phenomenon may be caused by the
hydrogen bond interaction between b-CD and MP. Thus, the
CP5 exhibits higher recognition capability towards MP than b-
CD. There is higher electrical signal with CP5-rGO modied
GCE.
(
mM) + 11.33 and I (mA) ¼ 0.233C (mM) + 20.918, and the corre-
lation coefficients are 0.973 and 0.985, respectively. As shown in
Table S1,† although some of the reported studies have lower
detection limits than our study, our study exhibits wider linear
range and the detection limit is a little different from the reported
The mechanism of MP on the modied electrode
The reaction mechanism of MP has been extensively studies. Therefore, our study may be suitable in MP sensing.
55–58
researched.
reduction peak at around ꢁ0.58 V that corresponds to the caused by 2-nitrophenol, 3-nitrophenol, 4-nitrophenol, nitro-
reduction of the nitro group (–NO ) to the hydroxylamine aniline, KCl, Na SO , MgCl , glucose, sucrose and CBR. These
Scheme 2 contributes to a sharp irreversible
Interference during the simultaneous detection of MP is
2
2
4
2
moieties (–NHOH) by a four-electron reduction process. Then, have been studied with the CP5-rGO-modied GCE, and the
during the anodic scan, the hydroxylamine moieties are chemical structures of these interferences are shown at
reversibly oxidized to the nitroso group (–NO) with an oxidation Fig. S12.† The currents for the reduction of 20 mM of MP at the
peak (around 0 V). The nitroso materials are reversibly reduced CP5-rGO/GCE are compared with the signal obtained in the
to the hydroxylamine group and have another reduction peak at presence of a 50-fold higher concentration of interfering
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1
Fig. 5 H NMR spectra (500 MHz, DMSO-d
6
, 298 K): (a) MP (10.00 mM); (b) a mixture of 10.00 mM MP and 10.00 mM CP5; (c) CP5 (10.00 mM).
species. The presence of these interferents does not affect the to DW (150 mL) under sonication, the solution was then l-
MP responses (Fig. 4D). These results indicate that the system trated by lter membrane (0.45 mM) for removing insoluble
has better selectivity than other methods.
solid matter. The waste water samples were collected from
The CP5-rGO/GCE is used to measure the content of MP in river water. The detection of MP in soil and waste water
soil and waste water samples employing standard addition practical samples is carried out by standard addition
methods to assess the feasibility of CP5-rGO-modied GCEs methods. Table 1 shows the recoveries ranging from 98.6% to
for real sample analysis. The procedure for preparing prac- 101.2% and RSDs ranging from 2.1% to 4.3% for MP. The
tical samples is elaborated as follows: soil (30 mg) was added proposed method for cationic pillar[5]arenes-functionalized
1
Fig. 6 H NMR spectra (500 MHz, DMSO-d
6
, 298 K): (a) MP (10.00 mM); (b) a mixture of 10.00 mM MP and 10.00 mM b-CD; (c) b-CD (10.00 mM).
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Scheme 2 The chemical reaction mechanism of MP in CP5-rGO-modified electrode.
Table 1 Determination of MP in soil and tap water samples
Science and Technology Commission of Chongqing, China (Grant
No. cstc2017jcyjAX0031).
Sample
Soil
Added (mM) Measured (mM) RSD (%) Recovery (%)
0
5
0
0
0
5
0
0
—
—
—
4.93 ꢃ 0.07
2.1
3.9
3.1
—
98.60
References
1
2
10.12 ꢃ 0.14
19.95 ꢃ 0.18
—
101.2
99.75
—
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2
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T. H. Kim, K. Kuca, D. Jun and Y. K. Jung, Bioorg. Med. Chem.
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4.97 ꢃ 0.07
9.97 ꢃ 0.13
20.23 ꢃ 0.23
4.3
3.2
2.9
99.4
99.7
101.15
1
2
reduced graphene-modied GCE has satisfactory accuracy
with potential applications in industrial and environmental
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Herein, we report a rapid and sensitive electrochemical sensor
based on cationic pillar[5]arene functionalized reduced graphene-
modied GCE CP5-rGO/GCE. These sensors were used to measure
MP by DPV for the rst time. Compared to b-CD-rGO/GCE, the
proposed CP5-rGO/GCE sensor exhibits excellent electrochemical
catalytic activity, rapid response, high sensitivity, good reproduc-
ibility and strong anti-interference ability. In addition, the
described method can detect MP in soil and waste water samples
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Acknowledgements
This study was nancially supported by the Program for Leading
Talents, the Education Commission of Chongqing, China (Grant 18 P. Mulchandani, W. Chen, A. Mulchandani, J. Wang and
No. KJ1712298, KJ121307), and the Basic Research Project of L. Chen, Biosens. Bioelectron., 2001, 16, 433.
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