Development and surface characterization of a bis(aminotriazoles) derivative based renewable carbon paste electrode for selective potentiometric determination of Cr(III) ion in real water samples
Introduction
The metal ions existence in body can be essential or toxic depending on their concentration levels. The standard concentration of elements in body is beneath the allowable level range that is crucial for the vital body physiological functions [1]. Cr (III) is essential for normal fat and carbohydrate metabolism and its deficiency can result in cardiovascular diseases and diabetes. However, excess amount of Cr(III) can be carcinogenic and can lead to digestive problems and kidney or liver harm [2], [3]. The adequate regular dietary intake for chromium is 50–200 g per day in adults [4]. Chromium ion is essential in industry and environment as well, so the development of a selective, sensitive and quick method for its determination in trace concentrations is a challenging task. Reported analytical techniques have been employed for Cr(III) determination like spectrophotometry [5], [6], [7], fluorimetry [8], atomic absorption spectroscopy [9], [10], high performance liquid chromatography (HPLC) [11], ion chromatography [12], etc., but there are disadvantageous in terms of cost and routine analysis. The continuous growing in ion selective electrode (ISE) field is due to its relatively low cost and maintenance. Moreover, the potentiometric measurements using ISEs are non-destructive and are characterized by high selectivity and sensitivity, speed, portability, no sample pretreatment and ease of preparation [13], [14], [15], [16], [17], [18], [19]. Carbon paste electrode (CPE) is heterogeneous carbon electrode of composite nature made of graphite powder as an electrical conductor embedded in a suitable binder providing the mechanical stability of the paste [20], [21], [22], [23]. CPEs are characterized by low background current, ease of fabrication and its surface renewability [24], [25], [26], [27], [28], [29].
Different types of ionophores have been introduced for the fabrication of cation selective electrodes for example, crown ethers, porphyrins, calixarenes, Schiff’s bases, macrocyclic compounds, metal chelates and ligands which are a category of supramolecular receptors with rigid cavities that can complex with a large variety of cations and the used ionophore efficiency depends on the high mobility, flexibility and lipophilicity of it [30]. Many ionophores were used in fabrication of Cr(III) ion selective electrode as reported [30], [31], [32], [33], [34], but triazoles exhibited
a large number of functions such as catalysts and inclusion compounds [30]. In addition, many reported papers have utilized triazole derivatives as a sensing material or ionophores for determination of metal ions due to their selective complexation ability, lipophilicity and conformational flexibility [30], [35], [36], [37].
In this research work, a novel, highly selective and sensitive carbon paste based sensor modified with two triazole rings derivative namely 1,3-bis[4-amino-5-benzyl-1,2,4-triazol-3-ylsulfanyl]propane, as an electroactive material, was fabricated for the determination of chromium(III) ions. Selectivity and experimental conditions affecting the sensor response were studied and optimized. The proposed synrhesized sensor was applied in analysis of Cr(III) in variant real water samples.
Section snippets
Reagents and samples
Analytical grade reagents were used in this work. A stock solution of 0.1 mol L−1 Cr(III) was prepared from a sufficient quantity of CrCl3·6H2O (Purity ≥98.0%) supplied from Sigma-Aldrich, in bidistilled water and buffered at pH = 4.5. The diluted solutions were prepared day by day via appropriate dilution from stock solution. In interference studies, the used metal solutions were made from analytical category chloride salts acquired from El Nasr Company. Graphite powder (synthetic 1–2 μm,
The effect of carbon paste composition on the sensor’s response
The nature and amount of electroactive material and plasticizer determine the selectivity and accuracy of carbon paste electrode. The target ion-ionophore interaction can be selective for several causes: the analyte ion size may fit the ionophore cavity, or the functional polar groups of the ionophore may form a complex with the target ion specifically, etc. This complexation selectivity and stability of the formed complex between ion and ionophore translates into the electrode’s potentiometric
Conclusion
A novel Cr(III) ion carbon paste electrode was developed by application of 1,3-bis(4-amino-5-benzyl-1,2,4-triazol-3-ylsulfanyl)propane as a neutral carrier. The results showed that this sensor is a good addition to the existing list of Cr(III) potentiometric sensors as it showed an enhancement in selectivity and sensitivity. This effortless, inexpensive and renewable Cr(III) sensor can be served as an indicator electrode in potentiometric titration of Cr(III) against EDTA and can also be
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgement
The authors would like to thank all persons, Cairo University and institutions that participated in production of this work either by advice or by technical helpful.
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