Abstract
The two adsorptive stripping voltammetric approaches for detection and quantitative determination of diethyl (2E)-2-{(2E)-[1-(4-methylphenyl)imidazolidin-2-ylidene]hydrazinylidene}butanedioate (DIB)—a novel molecule of medical importance—using two sensitive sensors based on modified glassy carbon electrodes as reusable sensors, were developed for the first time. The proposed electrochemical methods are based on adsorptive/reductive behaviour of DIB at two modified carbonic electrodes: a bismuth film-modified glassy carbon electrode (BiF/GCE) and a lead film-modified glassy carbon electrode (PbF/GCE). The electron gain mechanism for the electrochemical reduction of DIB on both developed sensors was proposed for the first time. To achieve the highest sensitivity in adsorptive stripping determinations, various experimental variables (e.g. the composition and pH of the supporting electrolytes, deposition conditions of bismuth and lead films, concentrations of plating solutions, accumulation times and potentials of DIB, etc.) were extensively examined. The comparison of validation parameters obtained during the determination of DIB at two sensors was presented. The excellent linear correlation was found between the monitored adsorptive stripping voltammetric peak current and the DIB concentration in the range of 15–600 μg L−1 at an accumulation time of 30 s (with LOD = 4.2 μg L−1 and LOQ = 14.0 μg L−1) using the BiF/GCE as a sensor. Furthermore, the excellent linear relationship was confirmed between the monitored adsorptive stripping voltammetric peak current and the DIB concentration in the range of 9–900 μg L−1 at an accumulation time of 10 s (with better LOD = 1.5 μg L−1 and LOQ = 5.0 μg L−1), employing the PbF/GCE as a sensor. The two optimized adsorptive stripping voltammetric approaches—as facile, sensitive, reliable and inexpensive—were successfully used as first methods for the quantitative analysis of a novel anticancer agent (DIB) in its pure pharmaceutically acceptable form. However, the practical applicability of square-wave adsorptive stripping voltammetric determination of the electroactive DIB molecule at a PbF/GCE, as the modified electrode of higher sensitivity, was presented after its successful solid phase extraction from a real serum sample.
Highlights
A process for the preparation and applicability of diethyl (2E)-2-{(2E)-[1-(4-methylphenyl)imidazolidin-2-ylidene] hydrazinylidene}butanedioate (DIB) (CAS number 1485685-53-7) (Fig. 1) has been patented previously
The structural characterization (1H NMR and 13C NMR spectral data including HMBC, HMQC and elemental analyses) and pharmacological characterization of diethyl (2E)2-{(2E)-[1-(4-methylphenyl)imidazolidin-2-ylidene]hydrazinylidene}butanedioate (DIB) have been provided in detail previously [1, 2]. 1H NMR, 13C NMR and DEPT-135 13C NMR spectra of DIB are attached in Supplementary material (Figs S1–S3)
In our stripping voltammetric determinations of DIB, a glassy carbon was chosen as the support for the first environmentally friendly sensor that was prepared—a bismuth film-modified glassy carbon electrode (BiF/GCE)
Summary
A process for the preparation and applicability of diethyl (2E)-2-{(2E)-[1-(4-methylphenyl)imidazolidin-2-ylidene] hydrazinylidene}butanedioate (DIB) (CAS number 1485685-53-7) (Fig. 1) has been patented previously. The prepared sensors were cleaned electrochemically for their reusability For this purpose, the lead or bismuth film (deposited on GCE) from the preceding measurement was removed by polarizing the electrode at a potential 1.0 V for 2 s two times in the analysed stirred solution. The stripping voltammetric measurements were carried out in underaerated solutions as oxygen is reduced on the surface of BiF/GCE in one stage at the potential outside a reduction range of this working sensor. DIB was accumulated by adsorption on the surface of PbF/ GCE, as a working sensor, at the potential − 0.6 V for 30 s During all these steps, the solution was stirred continuously employing a magnetic stirring bar. The square-wave adsorptive stripping voltammetric (SW-AdSV) procedure, using PbF/GCE as a working sensor, was used for the quantitative determination of DIB in real serum samples
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