Development of an electrochemical sensor of endocrine disruptor bisphenol A by reduced graphene oxide for incorporation of spherical carbon nanoparticles

Accepted Manuscript Development of an electrochemical sensor of endocrine disruptor bisphenol A by reduced graphene oxide for incorporation of spherical carbon nanoparticles

Thiago C. Canevari, Maura V. Rossi, Anamaria D.P. Alexiou PII: DOI: Reference:

S1572-6657(18)30709-4 doi:10.1016/j.jelechem.2018.10.044 JEAC 12684

To appear in:

Journal of Electroanalytical Chemistry

Received date: Revised date: Accepted date:

31 July 2018 19 October 2018 19 October 2018

Please cite this article as: Thiago C. Canevari, Maura V. Rossi, Anamaria D.P. Alexiou , Development of an electrochemical sensor of endocrine disruptor bisphenol A by reduced graphene oxide for incorporation of spherical carbon nanoparticles. Jeac (2018), doi:10.1016/j.jelechem.2018.10.044

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ACCEPTED MANUSCRIPT Development of an electrochemical sensor of endocrine disruptor bisphenol A by reduced graphene oxide for incorporation of spherical carbon nanoparticles. Thiago C. Canevari*, Maura V. Rossi and Anamaria D. P. Alexiou. Engineering School, Mackenzie University Presbyterian, 01302-907 São Paulo, SP, Brazil; *

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Corresponding author

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Tel/Fax: (+55) 11 2114-8884

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E-mail address: [email protected]

Abstract

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This work describes the synthesis of graphene oxide (GO) and its reduction using only carbon

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nanoparticles with no conventional chemical reducer or external energy. The reduced graphene oxide formed through the incorporation of the carbon nanoparticles (rGO-CNPS)

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was characterized by HR-TEM techniques, UV-vis, Raman spectroscopy and

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electrochemical techniques. The rGO-CNPS nanomaterial was incorporated on the surface of the printed carbon electrode and used to determine the endocrine interferent bisphenol A.

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The SPE-rGO-CNPS electrode presented excellent response for bisphenol A at

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concentrations varying from 7.5 × 10-9 to 2.6 × 10-7 mol L-1 in PBS, pH 7 with sensitivity 189.5 µmol L-1 and detection limit of 1 × 10-9 mol L-1. The electrode also presented excellent performance even in the presence of the main phenolic interferences and was used for determination of bisphenol A in plastic-bottled drinking water.

Keywords: Reduced graphene oxide, Carbon nanoparticles, Electrochemical sensor, Bisphenol A.

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ACCEPTED MANUSCRIPT 1. Introduction Carbon-based nanomaterials have been being increasingly studied since the discovery of graphene, due to the possibility of formation of different nanomaterials of different sizes and crystalline structures. The main carbon nanomaterials are: fullerenes; carbon

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nanoparticles, also denominated quantum dots of graphene or quantum dots of carbon, that

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both have 0D structures, carbon nanotubes of 1D structure; graphene with 2D structure; and

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graphite with 3D structure [1]. The different structures give nanomaterials different physical and chemical properties that directly influence their applications. Among the different

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carbon-based nanomaterials, two different types of graphene; graphene oxide (GO) and

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reduced graphene oxide (rGO), are being studied because they can be easily obtained from graphite, besides having many intrinsic properties and have surfaces that are readily modified

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[2,3]. The difference between GO and rGO is in the composition of the graphene sheet that

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makes up part of both species and has sp2 hybridization. In GO, there are many functional groups, as a result of the graphite oxidation process. These defects arise in the graphene

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sheets and are characterized by the change of hybridization from Csp2 to Csp3–O. The

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changes in GO cause significant changes in its conductive properties and are often considered as insulating [4]. Thus, the reestablishment of the conductive properties characterized by the

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increase of carbon atoms with sp2 hybridization is carried out by means of reduction of the GO, giving rise to a species called rGO. This reduction process can be carried out by several routes, such as the use of chemical reducing agents [5,6], and thermal [7], electrochemical [8], microwave [9], plasma [10] and sonication processes [11]. It is important to emphasize that each reduction process will give rise to an RGO with different properties. However, the use of nanoparticles only as reducing agents of GO has not been reported. Due to the excellent

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ACCEPTED MANUSCRIPT properties of RGOs, such as good electrical conductivity, they have been widely used in the development of (bio)electrochemical sensors [12,13]. Metal nanoparticles are also widely used in the development of electrochemical sensors because they facilitate the electron transfer process at the electrode–solution interface

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by improving the sensitivity of the modified electrodes,14 however their use as reducing

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agents has been little reported. In contrast to metallic nanoparticles, carbon nanoparticles

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(CNPs) have been used as reducing agents [15], besides being used in the development of electrochemical sensors [16]. Carbon nanoparticles are characterized by having their bulk

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composed of sp2 carbons and a surface carrying different functional groups, mainly

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carboxylic groups and hydroxyl groups. In addition, the carbon nanoparticles are water soluble; have low toxicity; have a quantum confinement effect, because they are less than 10

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nm in size; and are photoluminescent [17,18].

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Bisphenol A is a chemical substance widely used as a monomer in the synthesis of various polymers [19]. However, bisphenol A is very toxic to living organisms, being

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classified as an endocrine interferent, capable of replacing many essential biological

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compounds, causing serious damage, besides favoring the appearance of cancer in humans [20]. It is important to emphasize that bisphenol A is not degraded by sewage treatment

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systems, and can thus reach riverbeds and natural sources of water. Therefore, different analytical methods are employed to determine bisphenol A, such as chromatography [21], fluorescence [22], calorimetry [23], UV-vis [24] and electrochemical methods [25]. The electroanalytical determination of bisphenol A can be performed a vast array (bio)sensors achieved by modifications of bare electrode surfaces using different nanomaterials, for example, metallic nanoparticles [26], rGO modified [27], carbon black [28], carbon nanotubes [29], polymers nanocomposite [30], and others [31]. The electrochemical method 3

ACCEPTED MANUSCRIPT presents advantages in relation to the others because it can be used in situ, does not require specific treatment of the sample, to have similar sensitivity, to be easy to use and to be less expensive in comparison to other analytical techniques. Therefore, the development of new nanomaterials that have good electrocatalytic activities for bisphenol A is important. In this

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work, the hybrid nanomaterial (rGO-CNPs) was prepared only for combination between

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CNPs and reduced graphene oxide and have been used to develop a sensitive electrochemical

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sensor to determine bisphenol A in real sample.

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2. Experimental

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2.1 Reagents

The reagents used were 1-propanol P.A (Losco Chemical), KOH (Synth), bisphenol

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A (Aldrich), hydroquinone (Aldrich), cathecol (Aldrich), resorcinol (Aldrich), graphite

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powder 92% (Mercadocar), sulfuric acid 98% (Synth), hydrochloric acid 37% (Synth), potassium permanganate (Nuclear), hydrogen peroxide 30% (CAAL). Phosphate buffer

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solution (PBS, 0.1 mol L-1, pH 7.0) was prepared from KH2PO4 (Synth) and NaOH (Synth).

2.2 Preparation of graphene oxide (GO).

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The synthesis of graphene oxide (GO) was performed stepwise by the following procedure [32] with some modifications: 5 g of graphite powder were dispersed in a beaker containing 500 mL of 98% sulfuric acid at room temperature employing a mechanical stirrer. After 10 min stirring, 1 g of KMnO4 was added. The mixture became green due to the formation of the manganese (VII) oxide. Then, four additional portions of KMnO4 (1 g each) were added until the green color of the solution decreased, indicating that the oxidizing agent had been consumed. After this oxidation procedure, 800 mL of ice-cold deionized water was 4

ACCEPTED MANUSCRIPT added slowly, because the procedure was extremely exothermic. The mixture remained for 30 min under stirring, and then a few drops of hydrogen peroxide were added until the color of the mixture changed from reddish to yellow. After standing, a clear yellow solid and colorless supernatant was obtained. Thereafter, solid was separated and dispersed in 500 mL

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of 5% hydrochloric acid solution and the mixture stirred for 20 min. After this procedure, the

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mixture was allowed to stand for 24 h, resulting in its complete decanting. After decantation,

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the product obtained was diluted in 500 mL of deionized water and kept under stirring for 30 min, and then the mixture was allowed to stand another 24 h until complete decantation. The

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solid obtained was separated by centrifugation at 4100 rpm. This procedure was repeated six

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times; it was observed that the supernatant was not colorless, so it was decided not to discard but to store it in a glass vial for further analysis. This supernatant was called the aqueous

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solution of GO.

2.3 Reduction process of graphene oxide.

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The transformation of graphene oxide (GO) into reduced graphene oxide (rGO) was

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performed by mixing 50 mL of GO aqueous solution with 10 mL alcoholic solution of carbon nanoparticles (NPC) obtained with time of 4.5 h by the technique of chronoamperometry

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[33]. This mixture was allowed to stand for 24 h giving rise to the rGO-CNPs nanomaterial. It is important to note that no external reducing agent was added to the mixture, nor was there any additional energy supplied; for example, heating, ultrasound, plasma or photo irradiation, and the reduction of GO was achieved only by the incorporation of the carbon nanoparticles. The process of GO reduction by the incorporation of carbon nanoparticles occurs possibly due to the presence of functional groups, mainly hydroxyl groups, in the aromatic structure of carbon nanoparticles [34]. 5

ACCEPTED MANUSCRIPT 2.4 Electrode preparation. The printed carbon electrodes (Dropsens) were modified by the addition of 9 μL of the solutions of rGO-CNPs, GO, CNPs and allowed to stand for 24 h. After this period, the printed carbon electrodes containing the nanomaterials were used in the electrochemical

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experiments. The volume of 9 μL of the rGO-CNPs solutions was selected, rather than others

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such as 6, 7, 8 and 10 μL, because of its better electrocatalytic response to bisphenol A. This

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study was performed employing differential pulse voltammetry, in PBS, pH 7, and the best electrocatalytic response shown of 9 uL can be due to a good distribution of rGO-CNPs onto

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electrode surface.

2.5 Apparatus

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High resolution electron microscopy (HR-TEM) analyses were obtained using a 200

with ultrafine carbon film.

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kV JEOL microscope. Samples of the nanomaterials were dispersed on copper grids coated

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Absorption measurements in the UV-vis region were performed using an Agilent

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model 8453 spectrophotometer. The nanomaterial samples were dispersed in distilled water and the measurements were performed using a quartz cuvette.

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The Raman spectra of the nanomaterials were obtained by means of a WITec alpha 300 R confocal Raman microscope, in which the nanomaterials were dispersed on a thin plate of silicon and dried at room temperature. The

electrochemical

measurements

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performed

by

means

of

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potentiostat/galvanostat, model 128 N, from Metrohm Autolab BV. The electrochemical cell used in the measurements was composed of the printed carbon work electrode (Dropsens) modified by the nanomaterials, an auxiliary electrode consisting of platinum wire and a 6

ACCEPTED MANUSCRIPT reference electrode of Ag/AgCl (3M). All measurements were performed in 20 mL of phosphate buffer solution, pH 7.0. A standard ethanol solution of bisphenol A, at 10 mM concentration, was prepared daily before the measurements. The measurements of electrochemical impedance spectroscopy (EIS) were obtained in the Fe(CN)6 -3/4 solution (1

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x 10-2 M in 1 M KCl) that was used as a probe molecule. The EIS study was realized

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employing potentiostat/galvanostat, model 206 N, from Metrohm Autolab BV with

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frequency range from 100 kHz to 0.1 Hz.

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3. Results and Discussion

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3.1 HR-TEM

Figure 1 shows the HR-TEM micrographs, at different magnifications, for the GO

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and CNPs-rGO nanomaterials. As can be seen in Figures 1a and b, the graphene oxide (GO)

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formed contains several sheets of graphene; some are small and isolated and others are large and have a wrinkled leaf shape. However, when GO is reduced by the incorporation of carbon

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nanoparticles (CNPs), the graphene sheets are separated and the nanocomposite rGO presents

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a surface highly decorated by carbon nanoparticles (Figure 1c). Another important feature is that the CNPs are smaller than 5 nm and crystalline with spaces between planes of 0.2 nm,

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referring to the plane of carbon with sp2 hybridization, as can be seen in the enlarged image of Figure 1d.

3.2 UV-vis and Raman spectroscopy. The spectra in the UV-vis region were obtained with the purpose of demonstrating the reduction of the graphene oxide by the incorporation of the carbon nanoparticles (CNPs). Figure 2a shows the UV-vis spectra obtained in water for the nanomaterials graphene oxide 7

ACCEPTED MANUSCRIPT (GO), reduced graphene oxide containing CNPs (rGO-CNPs) and CNPs as obtained. As can be seen, graphene oxide (GO) has two characteristic bands, at 227 and 300 nm. The band around 227 nm corresponds to the electronic transitions π → π* due to the presence of the covalent bonds between the Csp2 atoms that constitute the hexagonal rings. The band around

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300 nm corresponds to the transitions due to the presence of functional groups, mainly

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carboxylic and hydroxyl groups that are characteristic of graphene oxides [35]. However,

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when spherical carbon nanoparticles are incorporated into the surface of the graphene oxides, a change in the UV-vis spectrum occurs in comparison to GO, in which the band around 227

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nm shifts to 262 nm and the band around 300 nm disappeared demonstrating the reduction

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of the hexagonal GO rings and reestablishing the conjugate structure between the carbon atoms in the graphene sheet [36,37], indicating the formation of the nanomaterial (rGO-

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CNPs). The reduction process does not completely remove the functional groups present on

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the surface of the graphene oxide. The nanomaterial (rGO-CNPs) presented better electronic properties in comparison to the GO due to the reestablishment of the structure of the graphene

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[3].

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Raman spectroscopy was used to study the structural changes occurring when the carbon nanoparticles (CNPs) were incorporated onto the GO surface. The main change is due

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to the change in the sp2-sp3 hybridization of the carbons that make up the graphene sheet. Figure 2b shows the Raman spectra for GO, the rGO-CNPs nanomaterials, and the graphite used as the GO starting material (Figure 2b inserted). As can be seen, the Raman spectrum of the graphite has an intense band at 1578 cm-1, called the G-band, and two low-intensity bands at 1344 and 2715 cm-1, called the D and G' bands, respectively. These three bands are used to characterize carbon-based nanomaterials, where the D band refers to the defects present in the graphene structure, characterized by carbon atoms with sp3 hybridization. The 8

ACCEPTED MANUSCRIPT G band refers to the organized structure of the graphene planes, characterized by the presence of carbon atoms with sp2 hybridization, and the G' band refers to the harmonic originating from the band G [38]. When CNPs are incorporated into the GO surface, there is a decrease in the intensity of the D and G bands and an increase in the intensity of the G' band, indicating

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that the GO was reduced by the carbon nanoparticles (CNPs) giving rise to the nanomaterial

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(rGO-CNPs), in agreement with the UV-vis analyses. It should also be noted that the D and

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G bands of the rGO-CNPs nanomaterial were displaced in comparison to those of GO, indicating that there is interaction between rGO and the CNPs. This displacement suggests

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that CNPs are acting as reducing agents of GO. The low intensity of the G' band along with

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the position at 2780 cm-1 indicates that there are several layers of graphene bound due to the

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3.3 Electrochemical measurements

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π–π interaction [39], in accordance with the HR-TEM images.

Figure 3 shows the comparison between the electrocatalytic responses of the clean

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printed carbon electrode (SPE), modified with GO (SPE-GO) nanomaterials, carbon

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nanoparticles (SPE-CNPs) and rGO-CNPs (SPE- rGO-CNPs) in relation to determination of the endocrine-interfering bisphenol employing differential pulse voltammetry in 1 x 10-6 mol

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L-1 bisphenol A. As can be seen, both materials present an electrocatalytic response to bisphenol A, but the printed electrode modified with rGO-CNPs (SPE- rGO-CNPs) showed a better electrocatalytic response (a higher current intensity) compared to other modified electrodes, due to the synergistic effect between reduced graphene oxide and the carbon nanoparticles. Such a synergistic effect is due to the rGO presenting excellent conductive properties because the graphene structure is largely restored by the reduction process, together with the increase in electroactive area due to the presence of carbon nanoparticles, 9

ACCEPTED MANUSCRIPT resulting in an improvement in the electron transfer process [14]. Another important feature is that the printed electrode modified with rGO-CNPs showed a discrete shift in the oxidation potential to less positive values (0.529 V) compared to electrodes modified with GO (0.535 V) and the clean printed electrode (0.540 V). The best electrocatalytic response showed by

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the SPE-CNPs in relation to SPE-GO probably is caused by an increase in electroactive area

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due to the presence of carbon nanoparticles, which facilitates the electron transfer process in

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the interface electrode-solution.

Taking into account that electrooxidation of bisphenol A involve the proton transfer,

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the study of electrocatalytic current change with pH variation were performed in 0.7 x 10-6

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mol L-1 bisphenol A, as showed in the Figure 4. As can be seen, in pH 7, the electrode modified with rGO-CNPs showed higher electrocatalytic current in comparison other pH, so

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the pH 7 value, was chosen to be employed in all electrocatalytic study.

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The EIS measurements were realized to study the electron transfer process in the interface modified electrode-solution. In the analysis of Nyquist plots, Figure not showed,

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the screen printed electrode modified with rGO-CNPs (SPE- rGO-CNPs), (Rct=15,5 Ω)

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showed a better electron transfer process in relation to the bare screen printed carbon electrode (SPE) (Rct=222 Ω), modified with GO (SPE-GO) (Rct=23,2 Ω) and carbon

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nanoparticles (SPE-CNPs) (Rct=19,7 Ω) due to present lower value of charge transfer resistance (Rct). These results are in agreement with differential pulse voltammetry study showed in the Figure 3.

3.4 Electrochemical determination of bisphenol A. Figure 5 shows the determination of the endocrine interferent bisphenol A using the screen printed carbon electrode modified with rGO-CNPs (SPE- rGO-CNPs) by differential 10

ACCEPTED MANUSCRIPT pulse voltammetry, in PBS, pH 7. As can be seen in Figure 5a, the SPE- rGO-CNPs electrode presents a good electrocatalytic response to the determination of bisphenol A because the catalytic current increases when the concentration of bisphenol A increases. Figure 5b shows the calibration curve for the determination of bisphenol A by the SPE- rGO-CNPs electrode

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which presents a linear relationship between the current (i) and the increase of the

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concentration of bisphenol A. The measurements were carried out with the concentration of

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bisphenol A ranging from 7.5 × 10-9 to 2.6 × 10-7 mol L-1, in PBS, pH 7, which can be represented by the following equation: i (A) = (3.57 ± 0.03) × 10-5 + 189.5 (± 3.5) [bisphenol

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A] (µmol L-1), with n = 11 and r = 0.998. The detection limit calculated according to IUPAC

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[40], considering (S/N = 3), was 1 × 10-9 mol L-1. This limit of detection presented by the electrode SPE- rGO-CNPs was better than that of other electrodes modified with several

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types of nanomaterials; for example, Cu2O-rGO [8], carbon nanotubes [41], ionic liquid

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functionalized Zn-Al layered double hydroxide [42], magnetic nanoparticles decorated reduced graphene oxide [23], ordered mesoporous carbon modified nano-carbon ionic liquid

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[43] and nanographene-based tyrosinase [5]. Another important feature of the SPE- rGO-

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CNPs electrode is the high sensitivity presented to bisphenol A (189.5 μmol L-1), making this SPE- rGO-CNPs electrode useful in the construction of a practical electrochemical sensor for

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bisphenol A.

It known that bisphenol A electrooxidation occur by 2H and 2e participation in the electrode-solution interface [31]. Therefore, we can suggest that the electrocatalytic determination of bisphenol A by SPE- rGO-CNPs electrode will occur due the CNPs to present quantum confinement and act as electron source, and the rGO that have some carbon atoms with oxygenated groups (C–O, C=O, O–C=O) will act as proton source, Scheme 1.

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ACCEPTED MANUSCRIPT The peaks with potential around 0.15 V and 0.7 V are possibly the result of byproducts of the electrooxidation of bisphenol A [44] due to the increase of the current as result of the increase in the concentration of bisphenol A.

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3.5 Possible interferents in determination of bisphenol A.

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The versatility of the SPE- rGO-CNPs electrode was tested taking into account the

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determination of bisphenol A in the presence of possible phenolic interferents, such as hydroquinone (HQ), catechol (Cat) and resorcinol (RC). Differential-pulse voltammetry

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measurements were performed in phosphate buffer, pH 7.0, with the concentration of HQ,

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Cat and RC being 100 times higher than the concentration of bisphenol A (BP). A preliminary test was performed by adding HQ, Cat or RC (50 μmol L-1) only to the electrochemical cell

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containing the SPE-rGO-CNPs electrode. Supplementary Figure S1a shows that the SPE-

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rGO-CNPs electrode presents electrocatalytic activity for HQ and Cat at the same potential, with a single peak around E = 0.21 V and little sensitivity for RC, with a potential shoulder

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around 0.60 V (50 μmol L-1) of HQ, Cat and RC. These measurements were realized together

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with addition of different concentrations of BP (0.5 to 4 μmol L-1), as shown in supplementary Figure S1b. As can be seen the Figure, the SPE- rGO-CNPs electrode presents

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a good electrocatalytic response for bisphenol A in the presence of phenolic interferents. However, HQ, Cat and RC phenols showed little interference in the determination of BP in phosphate buffer pH 7.0, shifting the potential to more positive potentials (around 0.565 V) compared to the determination of bisphenol in the absence of phenolic interferents. The small shifting in the electrocatalytic potential of determination of bisphenol A is possibly due the increase of the double electric layer due to the adsorption of the interferents onto the surface of the electrode, making the transfer electrons in the interface electrode-solution difficult. It 12

ACCEPTED MANUSCRIPT is important to emphasize that the presence of interferents does not prevent the determination of bisphenol A.

3.6 Electrochemical determination of bisphenol A in real samples.

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The application of the SPE- rGO-CNPs electrode to the determination of bisphenol A

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in plastic-bottled drinking water was also tested. The measurements were performed in

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triplicate by the standard addition method, using plastic-bottled drinking water without previous treatment. No oxidation peak for bisphenol A was found in plastic-bottled drinking

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water, possibly because there was no bisphenol A present, or it was present in concentrations

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lower than the detection limit of the SPE- rGO-CNPs electrode. Therefore, the water was contaminated with successive additions of 50 μl of bisphenol A solution. The results obtained

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using the extrapolation method are summarized in Table 1.

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According to the results presented in Table 1, it can be said that the SPE- rGO-CNPs

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electrode is efficient in the practical determination of bisphenol A.

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3.7 Characteristics of the SPE- rGO-CNPs electrode. The reproducibility in the production of the electrode was 100% over the production

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of 10 electrodes. Another important feature is the high repeatability of bisphenol A measurement using the differential-pulse voltammetry technique. Of the 10 SPE- rGO-CNPs electrodes used, all presented electrocatalytic activity for bisphenol A (0.02 μmol L-1) with small deviation in current intensity, with standard deviation about 0.5%. The SPE- rGOCNPs electrode remained stable for more than one month. Table 2 shows the performance of the SPE- rGO-CNPs electrode in the determination of bisphenol A in phosphate buffer, pH 7, compared to other electrodes modified with graphene species. 13

ACCEPTED MANUSCRIPT 4.0 Conclusion. The reduction of GO through the incorporation of the carbon nanoparticles (CNPs) was proved by UV-vis and Raman spectroscopy techniques. CNPs, in addition to reducing GO, were incorporated into the surface of reduced graphene oxide (rGO-CNPs) as shown by

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HR-TEM micrographs. The synergistic effect between rGO and CNPs gave the nanomaterial

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(rGO-CNPs) excellent electrocatalytic properties in the determination of bisphenol A. The

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good sensitivity combined with the low detection limit and the ease of surface modification of the printed carbon electrode (SPE), makes the nanomaterial potentially useful in the

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preparation of electrochemical sensors for the determination of the endocrine interferent

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bisphenol A.

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Acknowledgements

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T.C.C acknowledges FAPESP for Research grant 2016/12519-9 and Mackpesquisa.

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References

[1] V. Georgakilas, J.A. Perman, J. Tucek and R. Zboril, Broad Family of Carbon

CE

Nanoallotropes: Classification, Chemistry, and Applications of Fullerenes, Carbon Dots,

AC

Nanotubes, Graphene, Nanodiamonds, and Combined Superstructures. Chem. Rev., 115 (2015) 4744−4822.

[2] L. Cao, M.J. Meziani, S. Sahu, Y-P. Sun, Photoluminescence Properties of Graphene versus Other Carbon Nanomaterials. Acc Chem Res., 46 (2013) 171-180. [3] S. Pei and H-M. Cheng, The reduction of graphene oxide. Carbon, 50 (2012) 3210–3228.

14

ACCEPTED MANUSCRIPT [4] C. Gomez-Navarro, J.C. Meyer, R.S. Sundaram, A. Chuvilin, S. Kurasch, M. Burghard, K. Kern and U. Kaiser, Atomic Structure of Reduced Graphene Oxide. Nano Lett., 10 (2010) 1144–1148. [5] L. Wu, D. Deng, J. Jin, X. Lu and J. Chen, Nanographene-based tyrosinase biosensor for

IP

T

rapid detection of bisphenol A. Biosens Bioelectron., 35 (2012) 193–199.

CR

[6] C.K. Chua and M. Pumera, The reduction of graphene oxide with hydrazine: elucidating its reductive capability based on a reaction-model approach. Chem Commun., 52 (2016) 72-

US

75.

AN

[7] A. Gopalakrishnan, P. Sahatiya and S. Badhulika, Low temperature, one-pot green synthesis of tailored carbon nanostructures/reduced graphene oxide composites and its

M

investigation for supercapacitor application. Mater Lett., 198 (2017) 46-49.

ED

[8] R. Shi, J. Liang, Z. Zhao, A. Liu and Y. Tian, An electrochemical bisphenol A sensor

PT

based on one step electrochemical reduction of cuprous oxide wrapped graphene oxide nanoparticles modified electrode. Talanta, 169 (2017) 37-43.

CE

[9] H. Qiu, F. Qiu, X. Han and J. Li, Microwave-irradiated preparation of reduced graphene

AC

oxide-Ni nanostructures and their enhanced performance for catalytic reduction of 4nitrophenol. Appl Surf Sci., 407 (2017) 509-517. [10] Y-W. Chi, C-C. Hu, K-P. Huang, H-H. Shen and R. Muniyandi, Manipulation of defect density and nitrogen doping on few-layer graphene sheets using the plasma methodology for electrochemical applications. Electrochim Acta., 221 (2016) 144–153.

15

ACCEPTED MANUSCRIPT [11] D. Voiry, J. Yang, J. Kupferberg, R. Fullon, C. Lee, H.Y. Jeong and H.S. Shin, Highquality graphene via microwave reduction of solution-exfoliated graphene oxide. Science, 23 (2013) 1413-1416. [12] E. Povedano, F.H. Cincotto, C. Parrado, P. Díez, A. Sánchez, T.C. Canevari, S.A.S.

T

Machado, J.M. Pingarrón and R. Villalonga, Decoration of reduced graphene oxide with

CR

17β-estradiol. Biosens Bioelectron., 89 (2017) 343–351.

IP

rhodium nanoparticles for the design of a sensitive electrochemical enzyme biosensor for

AN

overview. Nanoscale, 7 (2015) 6420–6431.

US

[13] Z. Wang and Z. Dai, Carbon nanomaterial-based electrochemical biosensors: an

[14] J. Chazalviel and P. Allongue, On the Origin of the Efficient Nanoparticle Mediated

M

Electron Transfer across a Self-Assembled Monolayer. J Am Chem Soc., 133 (2011) 762-

ED

764.

PT

[15] Q. Lu, J. Deng, Y. Hou, H. Wang, H. Li, Y. Zhang and S. Yao, Hydroxyl-rich C-dots synthesized by a one-pot method and their application in the preparation of noble metal

CE

nanoparticles. Chem Commun., 51 (2015) 7164-7167.

AC

[16] F.R. Baptista, S.A. Belhout, S. Giordanib and S.J. Quinn, Recent developments in carbon nanomaterial sensors. Chem. Soc. Rev., 44 (2015) 4433-4453. [17] Y. Wang and A. Hu, Carbon quantum dots: synthesis, properties and applications. J Mater Chem C., 2 (2014) 6921-6939. [18] S.N. Baker and G.A. Baker, Luminescent Carbon Nanodots: Emergent Nanolights. Angew Chem Int Edit., 49 (2010) 6726-6744.

16

ACCEPTED MANUSCRIPT [19] N. Salgueiro-González, S. Muniategui-Lorenzo, P. López-Mahía, D. Prada-Rodríguez, Trends in analytical methodologies for the determination of alkylphenols and bisphenol A in water samples. Anal. Chim. Acta., 962 (2017) 1-14. [20] D.G. Skledar, L.P Mašič, Bisphenol A and its analogs: Do their metabolites have

IP

T

endocrine activity? Environ Toxicol. Phar., 47 (2016) 182-199.

CR

[21] C. Nicolucci, S. Errico, A. Federico, M. Dallio, C. Loguercio, N. Diano, Human Exposure to Bisphenol A and Liver Health Status: Quantification of Urinary and Circulating

US

Levels by LC-MS/MS. J Pharmaceut. Biomed., 140 (2017) 105-112.

AN

[22] Y. Zhang, Y. Wang, W. Zhu, J. Wang, X. Yue, W. Liu, D. Zhang, J. Wang, Simultaneous colorimetric determination of bisphenol A and bisphenol S via a multi-level DNA circuit

M

mediated by aptamers and gold nanoparticles. Microchim. Acta., 184 (2017) 951-959.

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[23] Y. Zhang, Y. Cheng, Y. Zhou, B. Li, W. Gu, X. Shi and Y. Xian, Electrochemical sensor

107 (2013) 211–218.

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for bisphenol A based on magnetic nanoparticles decorated reduced graphene oxide. Talanta,

CE

[24] N.K. Temel and R Gürkan, A micellar sensitized kinetic method for quantification of

1200.

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low levels of bisphenol A in foodstuffs by spectrophotometry. Anal Methods., 9 (2017) 1190-

[25] Y. Zhou, L. Yang and Y. Dang, A novel electrochemical sensor for highly sensitive detection of bisphenol A based on the hydrothermal synthesized Na-doped WO3 nanorods. Sensors Actuat B-Chem., 245 (2017) 238–246.

17

ACCEPTED MANUSCRIPT [26] R. Zhang, Y. Zhang, X. Deng, S. Sun and Y. Li. A novel dual-signal electrochemical sensor for bisphenol A determination by coupling nanoporous gold leaf and self-assembled cyclodextrin. Electrochim. Acta. 271 (2018) 417-424. [27] Y. Li, H. Wang, B. Yan and H. Zhang. An electrochemical sensor for the determination

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of bisphenol A using glassy carbon electrode modified with reduced graphene oxide-

IP

silver/poly-L-lysine nanocomposites. J. Electroanal. Chem., 805 (2017) 39–46.

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[28] N. B. Messaoud, A. A. Lahcen, C. Dridi and A. Amine. Ultrasound assisted magnetic imprinted polymer combined sensor based on carbon black and gold nanoparticles for

US

selective and sensitive electrochemical detection of Bisphenol A. Sensors Actuat B-Chem.,

AN

276 (2018) 304–312.

[29] W. Wang, X. Yang, Y.X. Gu, C.F. Ding and J. Wan. Preparation and properties of

M

bisphenol A sensor based on multiwalled carbon nanotubes/Li4Ti5O12- modified electrode,

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Ionics 21 (2015) 885-893.

[30] F. Tan, L. Cong, X. Li, Q. Zhao, H. Zhao, X. Quan and J. Chen. An electrochemical

PT

sensor based on molecularly imprinted polypyrrole/graphene quantum dots composite for

CE

detection of bisphenol A in water samples, Sens. Actuators B., 233 (2016) 599-606. [31] Dhanjai, A. Sinha, L. Wu, X. Lu, J. Chen and R. Jain. Advances in sensing and

AC

biosensing of bisphenols: A review. Anal. Chim. Acta 998 (2018) 1-27. [32] A.M. Dimiev and J.M. Tour, Mechanism of Graphene Oxide formation. ACS Nano, 8 (2014) 3060–3068. [33] T.C Canevari, M. Nakamura, F.H Cincotto, F.M. de Melo and H.E. Toma, High performance electrochemical sensors for dopamine and epinephrine using nanocrystalline

18

ACCEPTED MANUSCRIPT carbon quantum dots obtained under controlled chronoamperometric conditions. Electrochim Acta., 209 (2016) 464-470. [34] L. Shen, M. Chen, L. Hu, X. Chen and J. Wang. Growth and Stabilization of Silver Nanoparticles on Carbon Dots and Sensing Application Langmuir 29 (2013) 16135−16140.

IP

T

[35] Z. Luo, Y. Lu, L.A Somers and A.T.C. Johnson High Yield Preparation of Macroscopic

CR

Graphene Oxide Membranes. J. Am. Chem. Soc., 131 (2009) 898–899.

[36] J.M. Gonçalves, R.R. Guimaraes, C.V. Nunes Jr, A. Duarte, B.B.N.S. Brandao, H.E.

US

Toma and K. Araki, Electrode materials based on α-NiCo(OH)2 and rGO for high

AN

performance energy storage devices. RSC Adv., 6 (2016) 102504–102512. [37] D. Li, M.B. Muller, S. Gilje, R.B. Kaner and G. G. Wallace. Processable aqueous

M

dispersions of graphene nanosheets. Nat Nanotechnol., 3 (2008) 101–105.

ED

[38] M.S Dresselhaus, A. Jorio, M. Hofmann, G. Dresselhaus and R. Saito, Perspectives on

PT

Carbon Nanotubes and Graphene Raman Spectroscopy. Nano Lett., 10 (2010) 751–758.

CE

[39] A.C. Ferrari, Raman spectroscopy of graphene and graphite: Disorder, electron–phonon coupling, doping and nonadiabatic effects. Solid State Commun., 143 (2007) 47–57.

AC

[40] AM. Committee, Recommendations for the definition, estimation and use of the detection limit. Analyst, 112 (1987) 199-204. [41] L. A. Goulart, F. C. de Moraes, L. H. Mascaro, Influence of the different carbon nanotubes on the development of electrochemical sensors for bisphenol A. Mater. Sci. Eng. C. 58 (2016) 768-773.

19

ACCEPTED MANUSCRIPT [42] T. Zhan, Y. Song, X. Li, W. Hou, Electrochemical sensor for bisphenol A based on ionic liquid functionalized Zn-Al layered double hydroxide modified electrode. Mater. Sci. Eng. C 64 (2016) 354-361. [43] Y. Li, X. Zhai, X. Liu, L. Wang, H. Liu, H. Wang, Electrochemical determination of

T

bisphenol A at ordered mesoporous carbon modified nano-carbon ionic liquid paste

CR

IP

electrode. Talanta, 148 (2016) 362–369.

[44] H. Yin, Y. Zhou, S. Ai, Q. Chen, X. Zhu, X. Liu and L. Zhu, Sensitivity and selectivity

US

determination of BPA in real water samples using PAMAM dendrimer and CoTe quantum

AN

dots modified glassy carbon electrode. J.Hazard. Mat., 174 (2010) 236–243. [45] H. Fan, Y. Li, D. Wu, H. Ma, K. Mao, D. Fan, B. Du, H. Li and Q. Wei, Electrochemical

M

bisphenol A sensor based on N-doped graphene sheets. Anal. Chim. Acta., 711 (2012) 24-

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28.

[46] P. Deng, Z. Xu and Y. Kuang, Electrochemically reduced graphene oxide modified

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acetylene black paste electrode for the sensitive determination of bisphenol A. J. Electroanal.

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Chem., 707 (2013) 7–14.

[47] Y-C. Wang, D. Cokeliler and S. Gunasekaran, Reduced Graphene Oxide/Carbon

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Nanotube/Gold Nanoparticles Nanocomposite Functionalized Screen-Printed Electrode for Sensitive Electrochemical Detection of Endocrine Disruptor Bisphenol A. Electroanalysis, 27 (2015) 2527 –2536. [48] H. Ezoji and M. Rahimnejad, Electrochemical behavior of the endocrine disruptor bisphenol A and in situ investigation of its interaction with DNA. Sensors Actuat B-Chem., 274 (2018) 370-380.

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ACCEPTED MANUSCRIPT Figures and Tables captions

Figure 1: HR-TEM images at different magnifications of nanomaterials GO (a, b) and rGOCNPs (c) and CNPs (d).

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Figure 2: a) UV-vis spectra obtained in water for the nanomaterials GO, reduced GO

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containing carbon nanoparticles (rGO-CNPs) and CNPs. b) Raman spectra of the GO and

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rGO-CNPs nanomaterials. (Figure inserted: Raman spectrum of the graphite used in the preparation of the GO).

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Figure 3: Electrocatalytic responses of the cleaned carbon electrode (SPE) and modified

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with GO nanomaterials (SPE-GO), carbon nanoparticles (SPE-CNPs) and rGO-CNPs (SPErGO-CNPs) in relation to determination of the endocrine interfering bisphenol A. The

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measurements are performed employing differential pulse voltammetry.

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Figure 4: Study of variation of electrocatalytic current with pH. Measurements performed in

pulse voltammetry.

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PBS, with pH changing from 3 to 9, in 0.7 x 10-6 mol L-1 bisphenol A, employing differential

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Figure 5: a) Determination of the endocrine interferent bisphenol A by the printed carbon electrode modified with rGO-CNPs (SPE-rGO-CNPs) using the technique of differential-

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pulse voltammetry; b) Calibration curve I × [bisphenol A] obtained by electrode SPE- rGOCNPs. Measurements performed in phosphate buffer, pH 7.0. (Error bars 0.1%)

Scheme 1: The possible reaction mechanism of bisphenol A on the electrode SPE- rGOCNPs.

Table 1: Recovery results of plastic-bottled drinking water contaminated with bisphenol A. 21

ACCEPTED MANUSCRIPT Table 2: Performance of the SPE- rGO-CNPs electrode in the determination of bisphenol A compared to other electrodes modified with graphene species.

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Added (µmol L-1)

*Found (µmol L-1)

Recovery %

Bisphenol A

0.08 0.5 1

0.077 0.487 1.02

96.3 97.4 102

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Potential

electrodes

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SPE-rGO-CNPs

0.529

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189.4

0.54

0.005

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0.053

14.48

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5.1417

0.49

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0.0181

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0.0008

0.4430

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0.56

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(µAµmol L-1)

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MNPs-

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GR/ABPE[46]

Sensitivity

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(This work)

Cu2O-rGO/GCE[8]

Detection limit

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CS/N-GS/GCE[45]

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Water sample

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rGO/GCE[23]

RGO/CNT/AuNPsSPE[47] CNT/TiO2/CPE [48]

CS/N-GS/GCE: nitrogen-doped graphene sheets (N-GS) and chitosan (CS) on glassy carbon electrode.Cu2O-rGO: cuprous oxide wrapped graphene oxide GR/ABPE: Reduced graphene oxide modified acetylene black paste electrode, MNPs-rGO: magnetic nanoparticles (MNPs)-reduced graphene oxide (rGO) composites, RGO/CNT/AuNPs-SPEs: reduced 27

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Graphical abstract

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ACCEPTED MANUSCRIPT Research Highligths Hybrid nanomaterial (rGO-CNPs)

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Reduced graphene oxide formed through the incorporation of the carbon nanoparticles

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Screen printed electrode modified

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