A novel sodium dodecyl benzene sulfonate modified expanded graphite paste electrode for sensitive and selective determination of dopamine in the presence of ascorbic acid and uric acid

Accepted Manuscript A novel sodium dodecyl benzene sulfonate modified expanded graphite paste electrode for sensitive and selective determination of dopamine in the presence of ascorbic acid and uric acid

Jing Zhang, Xin-he Song, Sa Ma, Xue Wang, Wen-chang Wang, Zhi-dong Chen PII: DOI: Reference:

S1572-6657(17)30282-5 doi: 10.1016/j.jelechem.2017.04.035 JEAC 3250

To appear in:

Journal of Electroanalytical Chemistry

Received date: Revised date: Accepted date:

4 February 2017 14 April 2017 21 April 2017

Please cite this article as: Jing Zhang, Xin-he Song, Sa Ma, Xue Wang, Wen-chang Wang, Zhi-dong Chen , A novel sodium dodecyl benzene sulfonate modified expanded graphite paste electrode for sensitive and selective determination of dopamine in the presence of ascorbic acid and uric acid. The address for the corresponding author was captured as affiliation for all authors. Please check if appropriate. Jeac(2017), doi: 10.1016/ j.jelechem.2017.04.035

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ACCEPTED MANUSCRIPT A novel sodium dodecyl benzene sulfonate modified expanded graphite paste electrode for sensitive and selective determination of dopamine in the presence of ascorbic acid and uric acid Jing Zhanga,b, Xin-he Songa, Sa Maa, Xue Wanga, Wen-chang Wanga,b, and Zhi-dong Chena,b,c,* School of Petrochemical Engineering, Changzhou University, Changzhou 213164,

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Jiangsu, PR China

Jiangsu Key Laboratory of Materials Surface Science and Technology, Changzhou

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University, Changzhou 213164, Jiangsu, PR China

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Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering,

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Changzhou University, Changzhou 213164, Jiangsu, PR China

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Abstract:

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Keyword: Dopamine; Expanded graphite; Sodium dodecyl benzene sulfonate; Electrocatalysis; Electrochemical Sensor. *

Corresponding author. Tel. / Fax: +86-519-86330239. E-mail address: [email protected] (Z. D. Chen). 1

ACCEPTED MANUSCRIPT 1. Introduction Dopamine (DA), as an important excitatory chemical neurotransmitter, plays a very important role in central nervous, renal, hormonal and cardiovascular system [1,2]. Abnormal DA concentration has been related with various diseases such as Schizophrenia, Parkinson’s disease and Alzheimer’s disease [3-5]. Therefore, the

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determination of DA is of great importance in the field of biomedical chemistry and

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neurochemistry treatment. The common analytical techniques frequently used for the

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determination of DA include high performance liquid chromatography [6], spectrophotometry [7], chemiluminescence [8], and gas chromatography-mass

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spectrometry [9]. Recently, electrochemical techniques have obtained much attention and exhibited promising application in determination of DA to their high sensitivity,

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simplicity, low cost and convenient for in-situ detection [10-16]. Dopamine is an electrochemically active compound that can be directly oxidized at an appropriate

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potential and a suitable electrode material, and many electrochemical sensors had

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been fabricated for the determination of DA. However, a major problem of electrochemical determination of DA in real biological matrices is the interference

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from the coexisting compounds such as ascorbic acid (AA) and uric acid (UA). DA, AA and UA are oxidized at nearly the same potential with poor sensitivity at bare

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(unmodified) electrode, and the overlap of their voltammetric responses makes the selective of DA determination highly difficult. At the physiological pH of 7.40, AA (pKa=4.10) and UA (pKa=5.4) exist in the anionic form, while DA is in the cationic form (pKa=8.87). Based on the different ion forms of DA, AA and UA, self-assembled monolayer and negatively charged polymer films, had been used to modify electrode for selective DA determination [17,18]. This work prepared a novel anionic surfactant modified electrode for selective determination of DA in the 2

ACCEPTED MANUSCRIPT presence of AA and UA. Surfactants, a special class of amphiphilic molecules, have been widely applied in electrochemistry to improve the property of the electrode/solution interface [19]. Surfactants including sodium dodecyl sulfate (SDS) [20], sodium dodecyl benzene

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sulfonate (SDBS) [21], hexadecyltrimethylammonium bromide (CTAB) [22], octyl phenol ethoxylate (Triton X-100) [23], were extensively used to disperse carbon

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nanotubes in water because of their charged groups (hydrophilic heads) attract to

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water and their alkyl chains (hydrophobic tails) adsorb on the surfaces of carbon nanotubes. Compared to other commonly employed surfactants such as SDS, SDBS

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could enhance the stability of carbon materials in water due to the π-like stacking of

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the additional benzene rings of SDBS onto the surface of graphite [21,24]. Zhou et al. prepared SDBS functionalized graphene for confined electrochemical growth of metal/oxide nanocomposites for fructose sensing [25]. This work self-assembled

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negatively charged SDBS monolayers onto expanded graphite (SDBS-EG) for selective determination of protonated DA in the presence of negatively charged AA

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and UA.

Expanded graphite (EG), as an abundant network pore structured graphite

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derivative, has been proven to be the promising material for potential applications such as adsorbent [26], battery [27] and sensor [28] because of its unique properties including excellent electrical conductivity, high porosity, large specific surface area, cheap price, and good chemical stability. EG was used as electrode materials for the determination of catechol [29], and simultaneous determination of 4-chlorophenol and oxalic acid [30]. Recently, EG based electrodes were prepared for highly sensitive determination of some potentially toxic and pathogenic synthetic dyes such as Sudan I [31], Sunset yellow [32] and simultaneous determination of Ponceau 4R 3

ACCEPTED MANUSCRIPT and Tartrazine [33] in our previous works. Due to the multiporous structure and high conductivity, EG could facilitate the adsorption of the compound and the charge transfer, and thus improved the sensitivity of resulting electrodes. In this work, we prepared SDBS modified expanded graphite (SDBS-EG) composites, and fabricated SDBS-EG paste electrode (SDBS-EGPE) for the sensitive and selective of DA in the

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presence of AA and UA.

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The SDBS-EG composites was conveniently prepared by the adsorption of SDBS

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on the surface of EG, and SDBS-EGPE was fabricated by mixing SDBS-EG composites with solid paraffin. The combination of the advantages of EG and SDBS

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made the proposed electrode showed enhenced electrocatalytic and selective activity

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toward the oxidation of DA. Based on the high electrocatalytic and selective responses to DA at SDBS-EGPE, a convenient electrochemical method was developed for the determination of DA. The designed sensor showed good

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performance with a wide linear range, a low detection limit, and reproducibility, stability, reusability and selectivity for the determination of DA. The proposed electrode was successfully applied in the determination of DA in the commercial

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dopamine hydrochloride injection sample. This method provided a useful tool for the

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determination of DA in biological samples. 2. Experimental 2.1 Reagents and Materials Dopamine hydrochloride, SDBS, paraffin, KMnO4, phosphoric acid, Na2HPO4, NaH2PO4, AA and UA were purchased form Aladdin Reagent Co., Ltd. (Shanghai, China). Flake graphite (FG, 99% purity, grain size 50 mesh) was obtained from Qingdao Haida Graphite Co., Ltd. (Qingdao, China). The commercial dopamine 4

ACCEPTED MANUSCRIPT hydrochloride injection sample (52.7 mM) was purchased from Guangzhou Baiyun Shan Ming Xing Pharmaceutical Co., Ltd. (Guangzhou, China). All the solutions were prepared with twice distilled water. The buffer for assay was 0.1 M phosphate buffer saline (PBS) prepared by mixing stock-standard solution of Na2HPO4 and

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NaH2PO4.

2.2 Apparatus

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Scanning electron microscopic (SEM) images of EG and FG were obtained on a

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JSM-6360LA SEM instrument equipped with an EX-54175 JMU energy dispersive

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X-ray spectrometer (Japan). A pHS-3C digital pH meter obtained from Shanghai INESA scientific instrument Co. Ltd. (Shanghai, China) with a combined glass

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electrode was used to adjust the pH value of the PBS buffer solution, which was used as the supporting electrolyte in the voltammetric experiments. Electrochemical

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experiments including cyclic voltammograms (CVs) and differential pulse

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voltammograms (DPVs) were performed with CHI 660D electrochemical workstation (CH Instruments Inc., USA) with a conventional three-electrode cell. An

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SDBS-EGPE was used as working electrode, a saturated calomel electrode (SCE) and a platinum wire were used as reference electrode and auxiliary electrode,

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respectively. All the electrochemical measurements were carried out at 298 K. 2.3 Preparation of EG and SDBS-EG EG was synthesized according to our previous method [31-33]. FG (12 g) was dispersed in the solution consisting of 144 mL concentrated phosphoric acid and 48 mL concentrated nitric acid. After stirring for 10 min at 298 K, 3 g KMnO4 was added into the black suspension solution. The black mixture was reacted and stirred for 1 h at 298 K, followed by washing with twice distilled water until neutral pH, and 5

ACCEPTED MANUSCRIPT drying successively at 353 K in a vacuum oven for 2 h. EG was obtained by expanding the resulting mixture at 1123 K for 30 s in a muffle furnace. SDBS-EG composites were prepared according to the following procedure. 1 g EG powder dispersed in 50 mL 1 mmol/L SDBS. The black mixture was reacted and

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SDBS-EG composites were dried with an infrared light.

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stirred for 5 min at 298 K, and followed by washing with twice distilled water.

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2.4 Preparation of SDBS-EG and EGPE

The SDBS-EGPE was prepared by a convenient procedure. 0.97 g SDBS-EG

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composites was firstly crushed and mixed with 0.03 g solid paraffin, followed by heating at 338 K in an oven and constantly stirring for mixing homogeneously. After

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cooled to room temperature, a portion of the resulting paste was packed firmly into one end cavity (4 mm in diameter) of the electrode body, and the surface was

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smoothed against an 80 g A4 printing paper. Electrical contact to the pastes was

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established by inserting a copper wire (2 mm in diameter) down the glass tube and into the back of mixture. As a control, EGPE were prepared with the same procedure

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by mixing 0.97 g EG with 0.03 g solid paraffin.

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2.5 Analytical procedure The CV measurements were performed from −0.1 V to 0.5 V to study the electrochemical behaviors of DA at electrodes. DPVs were obtained from -0.1 V to 0.5 V to oxidize DA, and the pulse amplitude and width were 50 mV and 20 ms, respectively. After every measurement, the electrode could be regenerated by CVs from 0.4 V to 1.2 V for 10 times. Unless otherwise stated, 0.1 mol/L pH 6.8 PBS buffer solution was used as a supporting medium for DA analysis. The data for

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ACCEPTED MANUSCRIPT condition optimization and calibration curve were the average of three measurements. 3. Results and discussion 3.1 Characterization

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Fig. 1 shows the SEM images of the FG and EG. The FG was the lamellar

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structure, and graphite layers of FG adhered each other (Fig. 1A, B). After expansion,

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the lamellar structure of FG was transformed to a vermicular structure by expansion along the c-axis of graphite crystal (Fig. 1C). The SEM image of EG exhibited a

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multiporous structure, and there were many irregular honeycomb micropores in the layers of graphite (Fig. 1 D). The multiporous structure enhanced the surface area of

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EG, which could facilitate the adsorption of SDBS and DA at EG.

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3.2 Electrochemical responses of DA at SDBS-EGPE and EGPE

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In 0.1 mol/L pH 6.8 PBS, SDBS-EGPE (Fig. 2, curve a) and EGPE (Fig. 2, curve b) did not show any detectable signal in the working potential range. When 500

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μmol/L DA were added into PBS, the CV of SDBS-EGPE exhibited a pair of stable and well-defined redox peaks at 0.2 and 0.13 V (Fig. 2, curve c), which corresponded

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to the redox of DA. Although these peaks also occurred at EGPE (Fig. 2, curve d), the peak currents were 1.85 times lower than those at EGPE. This result indicated the significant sensitizing effect of SDBS, which could be attributed to the electrostatic interactions between the protonated DA and negatively charged SDBS film present on the electrode surface. 3.3 Optimization of the condition for the SDBS-EGPE fabrication The adsorption time of SDBS in the expanded graphite had a significant 7

ACCEPTED MANUSCRIPT influence on the electrochemical response of DA at the SDBS-EGPE. As shown in Fig. 3A, the peak current of 500 μmol/L DA at the resulting SDBS-EGPE increased with the increasing time of SDBS from 1 to 5 min, afterwards the peak current decreased with a slight decrease in the mount of 5-30 min. Therefore, 5 min was

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selected for the adsorption of SDBS at EG. The dependence of the amount of solid paraffin on the oxidation current of DA at

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the resulting SDBS-EGPE was shown in Fig. 3B. The peak current decreased with

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the increasing amount of solid paraffin in the amount range of 0-11 wt. %. The decrease may due to the lower electrical conductivity of the electrode caused by the

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higher amount of solid paraffin. EG has a multiporous structure, and there are many

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honeycomb micropores in the graphite layers. The loosen graphite layers could be crushed and mixed uniformly without paraffin. The electrode prepared without paraffin was not very stable, and SDBD-EG could easily fall off from the end cavity

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of the electrode. Although SDBS-EGPE prepared without solid paraffin showed the maximum current response, the amount of 3.0 wt. % for paraffin was selected for the

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preparation of SDBS-EGPE considering the stability of SDBS-EGPE. 3.4 Effect of solution pH

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The effect of pH value of 0.1 mol/L PBS for the electrochemical detemination of 500 μmol/L DA at SDBS-EGPE was investigated over the pH of 5.8-7.8. As seen in Fig. 4A, with an increasing pH from 5.8 to 6.8 the DPV peak current increased, following with a decrease in the pH range of 6.8-7.8. The optimum pH value of 6.8 is very close to the physiological pH value, therefore, pH 6.8 of 0.1 mol/L PBS was chosen for the electrochemical detection of DA. The influence of pH value on the peak potential of DA at SDBS-EGPE in 0.1 mol/L PBS was also studied. The peak

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ACCEPTED MANUSCRIPT oxidation potential of DA at SDBS-EGPE linearly shifted to more negative potential with the increasing pH from 5.8 to 7.8 (Fig. 4B) and the regression equation for DA was Epa (V) = -0.032 pH + 0.382 (R2 = 0.993). The result indicated the electro-oxidation of DA reacted on SDBS-EGPE and the electron transfer was accompanied by proton transfer in the electrochemical process. The slope of the

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function of Epa vs. pH deviated from the theoretical value, they could be ascribed to

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the influence of paraffin and SDBS, and the slower electrode reaction.

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3.5 Effect of scan rate

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To further understand the electrochemical behaviour of DA at SDBS-EGPE with different scan rates was studied. The dependence of potential scan rate on the

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oxidation response of 500 μmol/L DA at SDBS-EGPE was investigated by cyclic voltammetry in 0.1 mol/L pH 6.8 PBS (Fig. 5A). As shown in Fig. 5B, the peak

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current increased linearly with the scan rate in the range of 25 to 250 mV/s, and the

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equation can be expressed as I (μA)=37.38+0.55 v (mV/s) (R2=0.998). The result indicates that the oxidation of DA at SDBS-EGPE surface was an adsorption

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controlled process.

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3.6 Linear range and detection limit Fig. 6 displays the DPVs of different concentrations of DA at SDBS-EGPE in 0.1 mol/L PBS. The peak current of DA at SDBS-EGPE increased with the increasing concentration of DA (Fig. 6A). As shown in Fig. 6B, the linear concentration range of SDBS-EGPE for DA was from 0.5 to 500 μmol/L, and the regression equations could be expressed as I (μA)= 0.156 C (μmol/L)+0.604 (R2=0.999). The SDBS-EGPE for DA had a high sensitivity of 2215 μA mmol/L-1 cm-2 and a low detection limit down to 0.027 μmol/L at the signal to noise ratio of 3. The 9

ACCEPTED MANUSCRIPT determination performance of the proposed SDBS-EGPE for DA in the presence of AA and UA was compared with other modified electrodes. As shown in Table 1, it was clear that SDBS-EGPE electrode had a wider linear range and higher sensitivity. The good performance could be attributed to the high surface area increased by the multiporous structure of EG and the enhanced accumulation of protonated DA via

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electrostatic interactions between positively charged DA and negatively charged

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SDBS.

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3.7 Reproducibility, Stability and Reusability

The reproducibility of SDBS-EGPE was examined at the solution containing of

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500 μmol/L DA, and the relative standard deviation (RSD) of current signals at six

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independently prepared SDBS-EGPE was 2.98%, indicating an excellent repeatability. When SDBS-EGPE was not in use, it was stored at 298 K. 85.3% of the

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initial responses of SDBS-EGPE for DA were remained after four weeks when using

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once per 7 days, showing a good stability of SDBS-EGPE. The regeneration of SDBS-EGPE was carried out by cycling voltammetry from -0.1 V to 0.5 V in 0.1

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mol/L pH 6.8 PBS for five times. The as-renewed SDBS-EGPE could restore 89.2% of the initial value for DA after six assay runs, showing an accepted reusability.

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3.8 Interference studies

DA, UA and AA coexist in the extracellular fluid of the central nervous system and serum. The ability to selectively determine these species has been a major goal of electroanalysis research. Considering the normal concentration of AA or UA in the biological fluids are about 100 μmol/L, the interference of 100 μmol/L AA and 100 μmol/L UA in DA determination was evaluated. In 0.1 mol/L pH 6.8 PBS, SDBS-EGPE and EGPE did not show any detectable signal in the working potential 10

ACCEPTED MANUSCRIPT range. When the 0.1 mol/L pH 6.8 PBS solution containing 100 μmol/L AA, no obvious oxidation peaks were observed at SDBS-EGPE (Fig. 7, curve a) and EGPE (Fig. 7, curve b), indicating that SDBS-EGPE and EGPE had obvious electrocatalytic activity toward the oxidation of AA. When the 0.1 mol/L pH 6.8 PBS solution containing 100 μmol/L AA, DA and UA, DPVs of SDBS-EGPE (Fig. 7, curve c)and

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EGPE (Fig. 7, curve d) exhibited two stable oxidation peaks at 0.15 and 0.27 V,

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which corresponded to the oxidation of DA and UA, respectively. Compared with

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EGPE, the peak current of DA at SDBS-EGPE was 5.1 times higher than those at EGPE, indicating the significant sensitizing effect of SDBS due to the enhanced

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accumulation of protonated DA via the electrostatic interaction between positively charged UA and negatively charged SDBS. Moreover, there was a noticeable

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decrease in the oxidation peak current for UA at SDBS-EGPE, and the peak current of UA at SDBS-EGPE was 11.7 times lower than those at EGPE, which was due to

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electrostatic repulsion between negatively charged UA and SDBS. The high

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selectivity for DA at SDBS-EGPE could benefit from the electrostatic interaction between DA and SDBS, and electrostatic repulsion between negatively charged UA

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and SDBS. Therefore, SDBS-EGPE had highly selective determination of dopamine in the presence of AA and UA. The interferences of other species (such as KCl,

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MgCl2, CaCl2 and glucose) on the determination of DA at SDBS-EGPE were examined. The responses of SDBS-EGPE to 100 μmol/L DA was not affected by additions of 5-fold concentration of CaCl2, and 10-fold concentration of KCl, MgCl2 and glucose, and values of RSD for responses of SDBS-EGPE to DA were less than 5.0%. 3.9 Analysis of food samples To evaluate the analytical reliability and potential application, the proposed 11

ACCEPTED MANUSCRIPT electrode was applied to the determination of DA in determine DA content in the commercial dopamine hydrochloride injection sample. The dopamine hydrochloride injection (standard concentration of DA 52.7 mmol/L) was obtained from Shanghai Harvest Pharmaceutical Co., Ltd. (Shanghai, China). When detecting DA in the dopamine hydrochloride injection using SDBS-EGPE, 2 mL dopamine hydrochloride

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injection sample was added into a 100 mL volumetric flask and diluted with 0.1

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mol/L pH 6.8 PBS. Recovery testing was carried out to demonstrate the validity of

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the proposed method. The results have been shown in Table 1, and the recoveries were 98.4 and 102.3%, respectively. The result indicated good accuracy of

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SDBS-EGPE for DA determination.

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4. Conclusions

The SDBS-EG composites was conveniently prepared by the adsorption of SDBS

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on the surface of EG, and a sensitive and selective method was developed for the

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electrochemical determination of dopamine by using SDBS-EG paste electrodes. Compared with EGPE, the SDBS-EGPEs remarkably enhanced the electrocatalytic

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oxidation signal of DA because of the multiporous structure of EG and the enhanced accumulation of protonated DA via the electrostatic interaction between positively

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charged UA and negatively charged SDBS. Based on the electrocatalysis activity, an electrochemical method was constructed for determination of DA using the DPV method. The proposed method for DA had a wide linear range, a low detection limit, acceptable fabrication reproducibility and stability, and excellent reusability. The SDBS-EGPE showed a high selectivity for DA in the presence of UA and AA due to the electrostatic repulsion between UA, AA and SDBS. The proposed electrode was successfully applied in the determination of DA in the commercial dopamine

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ACCEPTED MANUSCRIPT hydrochloride injection sample. This prepared SDBS-EGPE might provide a promising potential in biological or clinical target analysis. Acknowledgments This work was financially supported by the National Science Foundation of China

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(21105006), Natural Science Foundation of Changzhou (CE20165047), State Key Laboratory of Analytical Chemistry for Life science (SKLACLS1403), Jiangsu Key

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Laboratory of Advanced Catalytic Materials and Technology (BM2012110),

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Advanced Catalysis and Green Manufacturing Collaborative Innovation Center

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(Changzhou University, 213164), Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering and a Project Funded by the Priority Academic

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Program Development of Jiangsu Higher Education Institutions.

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References [1] S. Basu, P.S. Dasgupta, Dopamine, a neurotransmitter, influences the immune system, J. Neuroimmunol. 102 (2000) 113–124. [2] I. Seri, Cardiovascular, renal, and endocrine actions of dopamine in neonates and

PT

children, J. Pediatr. 126 (1995) 333–344. [3] P. Damier, E.C. Hirsch, Y. Acid, A.M. Graybiel, The substantia nigra of the

SC

disease, Brain 122 (1999) 1437–1448.

RI

human brain II. Patterns of loss of dopamine-containing neurons in Parkinson's

NU

[4] S. Ikemoto, Dopamine reward circuitry: Two projection systems from the ventral midbrain to the nucleus accumbens–olfactory tubercle complex, Brain Res. Rev.

MA

56 (2007) 27–78.

[5] M.C. Chuang, H.Y. Lai, J.A. Annie Ho, Y.Y. Chen, Multifunctional

D

microelectrode array (mMEA) chip for neural-electrical and neural-chemical

PT E

interfaces: Characterization of comb interdigitated electrode towards dopamine detection, Biosens. Bioelectron. 41 (2013) 602–607.

CE

[6] V. Carrera, E. Sabater, E. Vilanova, M.A. Sogorb, A simple and rapid HPLC–MS method for the simultaneous determination of epinephrine, norepinephrine,

AC

dopamine and 5-hydroxytryptamine: Application to the secretion of bovine chromaffin cell cultures, J. Chromatogr. B 847 (2007) 88–94. [7] A. Abbaspour, A. Khajehzadeh, A. Ghaffarinejad, A simple and cost-effective method, as an appropriate alternative for visible spectrophotometry: development of a dopamine biosensor, Analyst 134 (2009) 1692–1698. [8] X.D. Xu, H.Y. Zhang, H.M. Shi, C.L. Ma, B. Cong, W.J. Kang, Determination of three major catecholamines in human urine by capillary zone electrophoresis with chemiluminescence detection, Anal. Biochem. 427 (2012) 10–17. 14

ACCEPTED MANUSCRIPT [9] A. Naccarato, E. Gionfriddo, G. Sindona, A. Tagarelli, Development of a simple and rapid solid phase microextraction-gas chromatography–triple quadrupole mass spectrometry method for the analysis of dopamine, serotonin and norepinephrine in human urine, Anal. Chim. Acta 810 (2013) 17–24. [10] X. Zhang, Y.C. Zhang and L.X. Ma, One-pot facile fabrication of graphene-zinc

PT

oxide composite and its enhanced sensitivity for simultaneous electrochemical

RI

detection of ascorbic acid, dopamine and uric acid, Sens. Actuators, B 227 (2016)

SC

488–496.

[11] J.E. Choe, M.S. Ahmed, S. Jeon, Trouble free dopamine sensing by palladium fabricated

poly(3,4-ethylenedioxythiophene)

functionalized

NU

nanoparticles

grapheme, J. Electrochem. Soc. 163 (2016) B113–B118.

MA

[12] A. Erkal, I. Asik, S.Yavuz, A. Kariper, Z. Ustundag, Biosensor application of carbonaceous nanocoil material: preparation, characterization, and determination

PT E

163 (2016) H269–H227.

D

of dopamine and uric acid in the presence of ascorbic acid, J. Electrochem. Soc.

[13] D.B. Gorle, M.A.

Kulandainathan, Electrochemical sensing of dopamine at the

CE

surface of a dopamine grafted graphene oxide/poly(methylene blue) composite modified electrode, RSC Adv. 6 (2016) 19982–19991.

AC

[14] E.A. Khudaish, F. Al-Nofli, J.A. Rather, M. Al-Hinaai, K. Laxman, H.H. Kyaw, S. Al-Harthy,

Sensitive and selective dopamine sensor based on novel

conjugated polymer decorated with gold nanoparticles, J. Electroanal. Chem. 761 (2016) 80–88. [15] G.L. Zhang, P. He, W.R. Feng, S.S. Ding, J.C. Chen, L. Li, H.C. He, S.S. Zhang, F.Q. Dong, Carbon nanohorns/poly(glycine) modified glassy carbon electrode: Preparation, characterization and simultaneous electrochemical determination of

15

ACCEPTED MANUSCRIPT uric acid, dopamine and ascorbic acid, J. Electroanal. Chem. 760 (2016) 24–31. [16] T.C. Canevari, M. Nakamura, F.H. Cincotto, F.M. de Melo, H.E. Toma, High performance electrochemical sensors for dopamine and epinephrine using nanocrystalline

carbon

quantum

dots

obtained

under

controlled

chronoamperometric conditions, Electrochim. Acta 209 (2016) 464–470. T.C.

Tsai,

F.H. Huang,

PT

[17]

J.J.J. Chen,

RI

Selective detection of dopamine in urine with electrodes modified by gold nanod

SC

endrite andanionic self-assembled monolayer, Sens. Actuators, B 181 (2013) 179–186.

NU

[18] C.H. Chen, S.C. Luo, Tuning surface charge and morphology for the efficient detection of dopamine under the interferences of uric acid, ascorbic acid, and

MA

protein adsorption, ACS Appl. Mater. Inter. 7 (2015) 21931–21938. [19] X.R. Chen, D.L. Ji, Y.K. Zhou, S.H. Xia, J.H. Tong, K.B. Wu, Electrochemical

D

enhancement of long alkyl-chained surfactants for sensitive determination of

PT E

tetrabromobisphenol A, Electrochim. Acta 190 (2016) 490–494. [20] A.J. Blanch, J.G. Shapter, Surfactant concentration dependent spectral effects of

CE

oxygen and depletion interactions in sodium dodecyl sulfate dispersions of carbon nanotubes, J. Phys. Chem. B 118 (2014) 6288–6296.

AC

[21] M. Suttipong, N.R. Tummala, B. Kitiyanan, A. Striolo, Role of surfactant molecular structure on self-assembly: aqueous SDBS on carbon nanotubes, J. Phys. Chem. C 115 (2011) 17286–17296. [22] Y. Bai, I.S. Park, S.J. Lee, T.S. Bae, F. Watari, M. Uo, M.H. Lee, Aqueous dispersion of surfactant-modified multiwalled carbon nanotubes and their application as an antibacterial agent, Carbon 49 (2011) 3663–3671. [23] S.M. Fatemi, M. Foroutan, Study of dispersion of carbon nanotubes by Triton

16

ACCEPTED MANUSCRIPT X-100 surfactant using molecular dynamics simulation, J. Iran. Chem. Soc. 12 (2015) 1905–1913. [24] X.S. Yan, X.D. Zhang, H.L. Liu, Y.H. Liu, J. Ding, Y.S. Liu, Q. Cai, J.M. Zhang,

Fabrication

of

SDBS

intercalated-reduced

graphene

oxide/polypyrrole nanocomposites for supercapacitors, Synthetic Met. 196 (2014)

PT

1–7.

RI

[25] S.H. Zhou, D.L. Wei, H.Y. Shi, X. Feng, K.W. Xue, F. Zhang, W.B. Song,

SC

Sodium dodecyl benzene sulfonate functionalized graphene for confined electrochemical growth of metal/oxide nanocomposites for sensing application,

NU

Talanta 107 (2013) 349–355.

[26] F.S. Zhang, Q. Zhao, X. Yan, H.Y. Li, P. Zhang, L. Wang, T.Y. Zhou, Y. Li,

MA

L. Ding, Rapid preparation of expanded graphite by microwave irradiation for the extraction of triazine herbicides in milk samples, Food Chem. 197 (2016)

D

943–949.

PT E

[27] Y. Yan, L.B. Ben, Y.J. Zhan, X.J. Huang, Nano-Sn embedded in expanded graphite as anode for lithium ion batteries with improved low temperature

CE

electrochemical performance, Electrochim. Acta 187 (2016) 186–192. [28] Y. Yang, C.G. Tian, L. Sun, R.J. Lu, W. Zhou, K.Y. Shi, K. Kan, J.C.Wang,

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H.G. Fu, Growth of small sized CeO2 particles in the interlayers of expanded graphite

for

high-performance

room

temperature

NOx gas

sensors,

J. Mater. Chem. A 1 (2013) 12742–12749. [29] Y. Kong, Y. Xu, H. Mao, C. Yao, X. Ding, Expanded graphite modified with intercalated montmorillonite for the electrochemical determination of catechol, J. Electroanal. Chem. 669 (2012) 1–5. [30] F. Manea, C. Radovan, I. Corb, A. Pop, G. Burtica, P. Malchev, S. Picken,

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ACCEPTED MANUSCRIPT Simultaneous determination of 4-chlorophenol and oxalic acid using an expanded graphite-epoxy composite electrode, Electroanal. 20 (2008) 1719–1722. [31] J. Zhang, M.L. Wang, C. Shentu, W.C. Wang, Y. He, Z.D. Chen, Electrochemical detection of Sudan I by using an expanded graphite paste electrode, J. Electroanal. Chem. 685 (2012) 47–52.

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[32] J. Zhang, H.H. Zhu, M.L. Wang, W.C. Wang, Z.D. Chen, Electrochemical

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J. Electrochem. Soc. 160 (2013) H459–H462.

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Determination of Sunset Yellow Based on an Expanded Graphite Paste Electrode,

[33] J. Zhang, X. Wang, S.B. Zhang, W.C. Wang, M. Hojo, Z.D. Chen, An

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electrochemical sensor for simultaneous determination of Ponceau 4R and Tartrazine based on an ionic liquid modified expanded graphite paste electrode, J.

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Electrochem. Soc. 161 (2014) H453–H457.

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ACCEPTED MANUSCRIPT Figure captions Fig. 1. SEM images of FG (A,B) and EG (C,D). Fig. 2. CVs of the SDBS-EGPE (a,c) and EGPE (b,d) in 0.1 mol/L pH 6.8 PBS in absence (a,b) and presence (c,d) of 500 μmol/L DA. Scan rate: 50 mV/s. Fig. 3. Influences of adsorption time of SDBS (A) and content of solid paraffin (B)

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on the DPV oxidation peak current of 500 μmol/L DA at SDBS-EGPE. When one

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parameter changed other parameters were at their optimal values.

Fig. 4. Effect of pH value of PBS buffer solution (A) on the DPV oxidation peak

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current of 500 μmol/L DA at SDBS-EGPE, and the influence of pH value of

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stripping electrolyte (B) on the DPV oxidation potential of 500 μmol/L DA at SDBS-EGPE. When one parameter changed other parameters were at their optimal

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Fig. 5. CVs (A) of 500 μmol/L DA at SDBS-EGPE with different scan rates ranging

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current and scan rate (B).

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Fig. 6. DPVs of different concentrations of DA at SDBS-EGPE in 0.1 mol/L pH 6.8

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PBS buffer solution (A), insert: amplified response curve, and calibration curve for DA sensing at SDBS-EGPE (B).

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Fig. 7. DPVs of SDBS-EGPE (a) and EGPE (b) in 0.1 mol/L pH 6.8 PBS buffer solution containing 100 μmol/L AA, and DVPs of SDBS-EGPE (c) and EGPE (d) in 0.1 mol/L pH 6.8 PBS buffer solution containing 100 μmol/L AA, 100 μmol/L DA and 100 μmol/L UA.

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ACCEPTED MANUSCRIPT Table 1 The comparison of determination performance of SDBS-EGPE with other electrodes.

Linear

range

Detection

limit

Electrode

Refs. (μmol/L)

(μmol/L)

RGO–ZnO/GCEa

3–330

1.08

Pd/PEDOT/RGO/GCEb

1–200

0.14

GNR-CTP/GCEc

2–20

0.003

0.96-42.12

1.03

[13]

ERG/PMB/GCEd

b

1–280

Nanocrystalline c-dots/GCEg

0.05-2

DDAB-EGPEg

0.5-500

0.03

[15]

0.004

[16]

0.027

This work

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CNHs/PGLY/GCEf

[14]

0.017

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0.15–1.5

[12]

reduced graphene oxide-zinc oxide composite modified glassy carbon electrode. palladium nanoparticles dispersed poly(3,4-ethylenedioxythiophene) functionalized reduced

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AuNPs-PTAP/GCEe

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grafted

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Dopamine

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graphene oxide composite modified glassy carbon electrode. c

graphene nanoribbon/coal tar pitch composite modified glassy carbon electrode.

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reduced graphene oxide/poly(methylene blue) composite modified glassy carbon electrode. poly(2,4,6-triaminopyrmidine) decorated with gold nanoparticles modified glassy carbon

electrode.

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CNHs/PGLY, carbon nanohorns/poly(glycine) modified glassy carbon electrode.

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Nanocrystalline carbon quantum dots (C-dots) modified glassy carbon electrode.

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ACCEPTED MANUSCRIPT Table 2 Determination of DA in real plastic product samples. Sample

Added (μmol/L)

Dopamine hydrochloride

Found (μmol/L)

0

22.1±0.09

10

31.6±0.21

0

22.2±0.06

20

43.2±0.08

Recovery (%)

98.4%

injection 1

hydrochloride

102.3%

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injection 2

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ACCEPTED MANUSCRIPT Highlights  A surfactant modified graphite paste electrode was fabricated.  The electrode showed enhenced electrocatalytic and selective activity for dopamine.

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 The electrode was successfully applied in determination of

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dopamine in real sample.

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