Regular ArticleDevelopment of electrochemical sensor for the determination of palladium ions (Pd2+) using flexible screen printed un-modified carbon electrode
Graphical abstract
Electrochemical pathway for the determination of Pd2+ ions via CV.
Introduction
Palladium (Pd2+) is a soft silver-white important common metal and widely used in modern industrial applications, including chemical industry, metallurgy, fuel cell and dentistry due to its physical and chemical properties such as high melting point, corrosion resistance and catalytic properties [1], [2], [3]. Especially in the field of automotive catalytic converters and chemical catalysis, Pd2+ is widely used become significant and prevalent, which leads to the accumulation of Pd2+ in the environmental [4], [5], [6]. The Pd2+ compounds easily contaminate to biological and soil water samples from the industrial waste, which leads to potentially toxic and impact to carcinogenicity for human health such as skin problems, eye irritation, damage of DNA and cell mitochondria, and inhibition of enzyme activity [7], [8]. Hence, the accurate and trace level determination of Pd2+ is much important for human health, while the direct detection and removal of Pd2+ is still difficult in research community. Therefore, various analytical methods such as atomic absorption spectrometry (AAS), inductively coupled plasma mass spectrometry (ICP-MS), high performance liquid chromatography (HPLC), fluorescence spectrometry, and electrochemical methods have been developed for the low level determination of Pd2+ in environmental samples [9], [10], [11], [12], [13], [14], [15], [16]. Obviously compared with electrochemical method, all aforementioned methods are sensitive and highly expensive. However, the electrochemical method is easy to handle, cheaper and sensitivity for the determination of Pd2+ in environmental samples [17]. In past decades, several modified electrodes have been received much attention for the analysis of Pd2+ ions determination [14], [15], [18], [19], [20].
On the other hand, the commercially available screen printed carbon electrodes have raised much attention in electroanalytical chemistry owing to its simplicity, higher sensitivity and good selectivity [21], [22]. Notably, only few reports are available for the determination of Pd2+ exists within the literature. Bai et al. demonstrated in-situ polymerization of ion-imprinted membranes at graphene modified electrode for the determination of Pd with higher sensitivity using amperometric technique [14]. Rosolina et al. reported the determination of Pd using unmodified glass carbon electrode in organic medium for the determination of Pd in active pharmaceutical ingredients [17]. Awual et al., used ligand based efficient conjugate nanomaterials for the detection of Pd in the presence of a high amount of foreign competing cations [23]. Qin et al. developed 9-bromophenanthrene (9-BrP) as a fluorescent probe for the determination of Pd in lake water with excellent analytical performance [24]. Rigdon and Harrar found that Pd by controlled caloric matric methods with excellent electroanalytical characteristics using Pd(IV)/Pd(II) system in azide media [25]. These aforementioned modified electrodes have several drawbacks such as high cost, difficult to handle and expensive analytical techniques. To overcome this problems, the screen printed carbon electrode has several advantage in electrochemical sensors such as commercially available, user free and disposable [22]. Metters et al. used screen printed graphite microband electrodes with excellent electroanalytical properties towards electrochemical detection of NADH and nitrite [26]. Tan et al. showed excellent electroanalytical results using screen printed microelectrode arrays for the detection of acetaminophen, dopamine and nitrite [27]. Owing to excellent electroanalytical features of screen printed carbon electrode, herein we have utilized un-modified screen printed carbon electrode is an alternate choice for the determination of Pd2+ ions.
To the best of our knowledge, in this present study we have been developed new electrochemical sensor for the determination of Pd2+ ions using un-modified screen printed carbon electrode for the first time. The advantage of this proposed method is simple and low cost for the determination of Pd2+ ions with wide linear range and higher sensitivity. Owing to excellent electroanalytical performance, this sensor also exhibits to detect the Pd2+ ions in water samples using spiked method with satisfactory results.
Section snippets
Materials
Screen printed carbon electrode was purchased from Zensor R&D Co., Ltd., Taipei, Taiwan. Palladium chloride was supplied from Sigma-Aldrich. The pH solution of 0.5 M acetate buffer was prepared using glacial acetic acid and sodium acetate were adjusted using either H2SO4 or NaOH. All of used chemicals in this work were of analytical grade and all the solutions were prepared using doubly distilled water.
Apparatus
The electrochemical experiments were performed using CHI 900 electrochemical workstation with
Characterization
The surface morphology of un-modified bare SPCE was characterized by SEM as shown in Fig. 1. The SEM image of bare SPCE reveals that the uniform flake like morphology, the results are shown in Fig 1 (A) higher and (B) lower magnification. On the other hand, the Fig. 1(C) shows the Pd ions covered flake like morphological structure of SPCE, after the Pd2+ ions determination by CV.
In addition, the EDX spectrum also authenticates the presence of Pd on the SPCE surface after determination of Pd2+
Conclusions
In conclusion, we developed a simple, eco friendly and cost effective new system for electrochemical determination of Pd2+ ions using un-modified SPCE by DPV method. The un-modified SPCE showed a selective electrochemical determination of Pd2+ ions even in the 100 folds higher concentrations of possibly interfering metal ions. The excellent electroanalytical parameters (LOD, linear range, sensitivity) were achieved using un-modified SPCE towards the determination of Pd2+ ions. The proposed
Acknowledgments
The authors extend their appreciation to the International Scientific Partnership Program ISPP at King Saud University for funding this research work through ISPP#6. This project was supported by the National Science Council and the Ministry of Education of Taiwan (Republic of China).
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