We developed an enantioselective voltammetric sensor based on a carbon-paste electrode modified by enantiomorphic crystals of bromotriphenylmethane for the recognition and determination of tryptophan ...enantiomers. Enantiomorphic crystals of bromotriphenylmethane were obtained under the condition of Viedma ripening. The electrochemical and analytical characteristics of the sensor were studied. The proposed sensor was used to recognize and determine the enantiomers of L- and D-tryptophan in model solutions of pharmaceutical preparations and in human urine and blood plasma samples. The sensor is easy to manufacture and exhibits high reproducibility and stability. It was shown that, in using chemometric data processing, the presence of even slight differences between the voltammograms of enantiomers recorded using the proposed carbon-paste electrode is sufficient for their reliable recognition.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
To achieve satisfactory recognition and determination of tryptophan (TRP) enantiomers a chiral voltammetric sensor based on carbon black paste electrode (CBPE) containing Carboblack C powder and ...3-neomenthylindene (NMI) chiral selector is developed in this work. A possible recognition mechanism as well as chiral selectivity have been explained using the molecular dynamics simulation. It was shown that 3-neomenthylindene attracts to TRP enantiomers via Van der Waals and π-π-stacking interactions. Compared with D-TRP, the sensor indicates favorable chiral recognition towards L-TRP with a selectivity coefficient of 1.34. The higher response signal of L-TRP than D-TRP is due to the energetically more favorable interaction of 3-neomenthylindene with L-TRP, which is confirmed by a change in the total energy of the system. CBPE modified by NMI was characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR). The electrochemical and analytical characteristics of the sensor and conditions of the voltammogram registration were studied by differential pulse voltammetry (DPV). It was found that the oxidation of TRP enantiomers on CBPE/NMI is the diffusion-controlled process. The experimental results indicate a linear correlation between the peak currents of TRP enantiomers and their concentration in the range from 2.5 μM to 0.3 mM, leading to a detection limit of 1.71 μM and 2.23 μM for L- and D-TRP, respectively. The practical capabilities of the proposed sensor were demonstrated by analyzing human urine and blood plasma with satisfactory recoveries ranging from 95.2% to 99.0%. L-TRP was recognized in dietary supplements using projection to latent structures discriminant analysis. The present sensor also can detect the enantiomeric composition based on current signals with the different total concentrations of the mixture. The selectivity, stability, and reproducibility of the proposed sensor were studied as well.
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•A chiral sensor based on CBPE modified by 3-neomenthylindene (NMI) was developed.•Large differences in energy between π-π-stacking of NMI with L-, D-TRP were observed.•Compared with D-TRP, the sensor indicates favorable chiral recognition towards L-TRP.•The sensor correctly determined L- and D-TRP in real objects and enantiomeric mixture.•The recognition of L-TRP based dietary supplements using PLS-DA was successful.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We developed an enantioselective voltammetric sensor system based on glassy carbon electrodes modified by polyarylenephthalide composites with α-, β-, and γ-cyclodextrins for the selective ...recognition and determination of tryptophan (Trp) enantiomers. The electrochemical characteristics of the electrodes and surface morphology were studied by cyclic voltammetry, electrochemical impedance spectroscopy, and atomic force microscopy. The proposed sensor system with recording voltammograms by three electrodes and the chemometric processing of the data using principal component analysis and projections to latent structures discriminant analysis was used to recognize tryptophan enantiomers in food additives and to determine their manufacturer.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The electrochemical and analytical characteristics of enantioselective sensors based on glassy carbon electrodes modified by chelate complexes (bis(L-phenylalaninate) copper(II), ...glycinato-L-phenylalaninate copper(II), tris(L-phenylalaninate) cobalt(II), bis(L-phenylalaninate) zinc) are studied. It is found that the most promising sensor for determining tryptophan enantiomers is the sensor modified by copper(II) (bis)L-phenylalaninate. In determining tryptophan enantiomers, this sensor provides a linear concentration range from 6.25 × 10
–7
to 0.5 × 10
–3
M for L-tryptophan and from 5 × 10
–6
to 0.5 × 10
–3
M for D-tryptophan. The sensor is more sensitive to L-tryptophan. The proposed sensor was used for the recognition and determination of tryptophan enantiomers in human urine and plasma samples, and also in a mixture of enantiomers. The statistical assessment of the results of determinations by the spiked–found method indicates the absence of a significant systematic error.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
An enantioselective voltammetric sensor based on a glassy carbon electrode modified with a composite of a polyelectrolyte complex of chitosan, Carboblack C graphitized thermal carbon black, and ...3,4,9,10-perylenetetracarboxylic acid is developed for the recognition and determination of tyrosine enantiomers. The enantioselectivity of the sensor is due to the formation of self-organizing chiral nanoclusters of 3,4,9,10-perylenetetracarboxylic acid. The electrochemical and analytical characteristics of the sensor are studied. The proposed sensor is used to recognize and determine L- and D-enantiomers of tyrosine in samples of urine and human blood plasma, as well as in a mixture. To increase the probability of the recognition of tyrosine enantiomers in determining them in a mixture, the chemometric method of projection to latent structures is used. It is shown that the proposed sensor ensures the determination of the ratio of L- and D-enantiomers of tyrosine in a mixture with a high probability and a relative error of less than 8%.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
An enantioselective voltammetric sensor for the recognition of propranolol stereoisomers is developed based on a carbon-paste electrode modified with uracil supramolecular structures and the use of ...chemometric methods. The conditions for the formation of an enantioselective selector on the surface of graphite (graphene) particles and the selective registration of voltammograms of enantiomers, as well as the possibility of the recognition thereof, are studied by methods of molecular dynamics simulation and voltammetry.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A voltammetric sensor based on a glassy carbon electrode modified with a chitosan, Carboblack C graphitized carbon black, and molecularly imprinted polyarylene phthalide composite is developed for ...the selective detection of antibiotic clarithromycin. The polyarylene phthalide used for modification contains diphenylenethio- and diphenylene oxide fragments in a 1 : 2 ratio in the main polymer chain. Clarithromycin-imprinted polyarylene phthalide was obtained using the phase inversion method. The composition and morphology of the modifying coating were investigated by IR spectrometry and scanning electron microscopy. The electrochemical and analytical characteristics of the sensor were investigated by electrochemical impedance spectroscopy, cyclic voltammetry, and differential pulse voltammetry. Optimal conditions for recording the analytical signal were selected. Using Fe(CN)
6
3−/4−
as a probe, the linear range of the detected concentrations was found to be 1 × 10
–7
–5 × 10
–4
M with a limit of detection of 5.3 × 10
–8
M. Using a clarithromycin-imprinted polymer enhances the sensor sensitivity by nearly tenfold compared to the nonimprinted polymer. The proposed sensor was tested using urine, blood plasma, and various food samples (meat, milk), the recovery values were 90–96, 80, and 92%, respectively, with relative standard deviations not exceeding 10% in all cases.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Voltammetric sensors and a sensor system based on gold electrodes modified with polyarylenephthalides (chlorinated polyphthalidylidene fluorene and polyphthalidylidene diphenyl and brominated ...polyphthalidylidene diphenyl) for the identification of cysteine are developed. The surface morphology of the modified electrodes and electrochemical and analytical characteristics of the sensors are studied, the conditions for the electrochemical oxidation of cysteine and the production of an analytical signal are optimized. The proposed sensors and sensor system, with chemometric processing of response signals, allows recognizing manufacturers of cysteine-containing pharmaceutical preparations. The use of the voltammetric sensor system can significantly increase the percentage of correctly recognized samples in comparison with the registration of voltammograms on separate electrodes.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
New voltammetric sensors based on glassy carbon electrodes (GCEs) modified by poly(arylene phthalide) are studied. The electrochemical behavior of bisoprolol on GCEs modified by poly(arylene ...phthalide) is investigated. The effects of potential scan rate, time of accumulation on the electrode, pH of supporting electrolyte, and concentration on the current of bisoprolol electrooxidation are estimated. A procedure is developed for the voltammetric determination of bisoprolol on glassy carbon electrodes modified by poly(arylene phthalide). The dependence of the analytical signal on the concentration of bisoprolol is linear in the range 10
–6
–10
–5
M with the limit of detection (3.4–9.8) × 10
–8
M.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Using chemometrics, we developed a voltammetric method for the identification and discrimination of pharmaceuticals containing insulin and its analogues from various manufacturers. Their ...electrochemical behavior on glassy carbon electrodes modified with polyarylenephthalide films is studied; analytical characteristics are evaluated; and the optimal conditions for recording the analytical signal and the nature of electrode processes are determined. Some examples of the voltammetric identification and recognition of pharmaceutical products containing insulin are given.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
