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Vol 73, No 4 (2018)
- Year: 2018
- Articles: 11
- URL: https://journals.rcsi.science/1061-9348/issue/view/11432
Reviews
Determination of Dipeptidyl Peptidase-4 Inhibitors by Spectrophotometric and Chromatographic Methods
Abstract
Dipeptidyl peptidase-4 (DPP-4) inhibitors are a novel class of oral anti-diabetic agents used in the treatment of type 2 diabetes mellitus and work to enhance the effect of incretin hormones. There has been significant research on wide range of analytical techniques that could be useful in the estimation of DPP-4 inhibitors in formulations and biological matrices. Analytical methods such as ultraviolet (UV) spectrophotometry, mass spectroscopy, NMR spectroscopy, HPLC, high pressure thin layer chromatography, ultra performance liquid chromatography, liquid chromatography‒mass spectrophotometry and capillary zone electrophoresis have been reported for the estimation of DPP-4 inhibitors in single and/or in combination with other drugs. This comprehensive review covers most of the spectrophotometric and chromatographic methods described for the determination of sitagliptin, alogliptin, vildagliptin, linagliptin, saxagliptin and teneligliptin in pure forms, in different pharmaceutical dosage forms and biological fluids. From the review it can be deduced that a large number of chromatographic methods have been developed, and HPLC-UV methods have been commonly used in the detection and evaluation of DPP-4 inhibitors.
303-316
Methods of Determination of Antibiotic Residues in Honey
Abstract
Monitoring antibiotics residues in honey and honey products helps to assess the potential risk of these products to human health. These data provide an insight in the extent of antibiotic treatment that has been used during the beekeeping and enable the evaluation of potential environment pollution with antibiotic residues. This article offers an overview of methods for identification and determination of different antibiotics potentially present in honey, as well as of maximum residue limits for antibiotics in bee products, in particular honey. It is important to stress the importance of strict monitoring system and validation of analytical methods that will enable an accurate, precise and reliable determination of acceptable minimal concentrations of pollutants in honey.
317-324
Articles
Application of Silica Chemically Modified by Sulfur-Containing Groups to the Separation and Determination of Platinum and Rhenium in Catalysts Based on Aluminum Oxide
Abstract
Adsorbents based on silica chemically modified by sulfur-containing groups (dithiocarbamate, thiodiazolethiol, mercaptophenyl, and aminobenzothiazole) quantitatively extract (recovery ≥99%) platinum( IV) from solutions ranging from 4 M HCl to pH 6. Under the conditions of the adsorption separation of platinum(IV), rhenium(VII) is not extracted and remains in the solution. The subsequent quantitative (98–99%) adsorption of rhenium(VII) is achieved in the presence of a 1000-fold excess of tin(II) chloride. Adsorption on the surface of adsorbents leads to the formation of platinum(II) complexes with sulfur-containing groups, luminescent at 77 K on irradiation with UV light. The luminescence spectra of surface platinum( II) complexes are located in the region of 550–700 nm. In the adsorption of rhenium(III) in the presence of tin(II) chloride, intensely colored brown complexes of rhenium formed on the surface of adsorbents. Electron paramagnetic resonance showed that, in the surface complexes, rhenium is in the oxidation state 2+. Silicas chemically modified by sulfur-containing groups were used in the development of procedures for the sequential isolation and determination of platinum and rhenium in solutions after the decomposition of aluminum–platinum–rhenium catalysts.
325-333
Possibilities of the Determination of Matrix Elements of High-Purity Glasses of As–Se and As–S Systems by Inductively Coupled Plasma Atomic Emission Spectrometry
Abstract
Possibilities of inductively coupled plasma atomic emission spectrometry (ICP AES) as an alternative to X-ray spectrochemical analysis are estimated in the determination of matrix elements of glasses of As–Se and As–S systems. Standard solutions were prepared from pure elements As, Se and S. It was shown that the matrix elements of glasses can be determined with an expanded uncertainty of 0.05–0.1 mol %. The results of determinations by ICP AES and X-ray fluorescence spectrometry were compared; and it was found that by the attained performance characteristics, the results of ICP AES are highly competitive with the data of X-ray fluorescence spectrometry, but do not require sets of adequate solid reference samples.
334-343
Possibility of Comparison of the Similar Pharmaceuticals from Different Producers by Spectroscopic System Based on Hollow-Core Photonic-Crystal Fiber
Abstract
The results of complex studies of a possibility of the rapid analysis of solutions using a spectroscopic system based on a hollow-core photonic-crystal fiber are presented. Pharmaceutical preparations of vitamins B and C from various manufacturers were selected as test samples. The transformation of the transmission spectra of the fiber after filling hollow channels with an analyte solution was observed in the wavelength region of 350–1100 nm, depending on the type of the vitamin, producer, and concentration. Comparative quantitative estimates of the sensitivity, resolution, and error in determining the concentration of solutions are given. To increase the functionality of the spectroscopic system, it is suggested to use known chemometric methods and algorithms.
344-350
Characterization of Refuse Derived Fuel Using Thermogravimetric Analysis and Chemometric Techniques
Abstract
An approach for characterization of refuse derived fuel (RDF) using thermogravimetry and chemometric techniques was developed. For this purpose, a series of samples coming from lignocellulosic products (wood, cardboard, paper, newspaper) and plastics (polyethyleneterephthalate, high density polyethylene, polypropylene, polypropylene, nylon and polyvinylchloride), as well as their mixtures, were investigated by means of thermogravimetry (TG) in a temperature range between 25 and 800°C. The datapoints of TG diagrams (weight loss) were then subjected to principal component analysis in order to unravel similarities/ dissimilarities of the investigated samples. A classification was obtained according to their woody/petroleum derived origination. This classification was more evident if partial least square discriminant analysis was employed. Finally, a partial least square analysis was carried out for the determination of lignocellulosic content in the sample. The model was validated by application to samples with known mass fraction of lignocellulosic products. Finally, the model was applied to two RDF samples using fractions of their particle sizes from 1 mm to less than 0.032 mm, and the results were compared with their ultimate and proximate analysis.
351-357
Simultaneous Determination of Succinic Acid and Water-Soluble Vitamins by Ion-Pair High-Performance Liquid Chromatography
Abstract
A procedure is proposed for the determination of succinic acid, riboxin, nicotinamide, and riboflavin by ion-pair HPLC with UV detection. Owing to the addition of an ion-pair modifier to the mobile phase and the selection of gradient elution conditions, the optimal retention and resolution of peaks of the components to be determined are achieved. Specificity, linearity, accuracy, and precision of the developed procedure are proved on an example of the determination of active substances in the Cerebronorm® preparation.
358-363
Analysis of Niobium–Rare-Earth Ores by Inductively Coupled Plasma Mass Spectrometry
Abstract
To determine the composition of niobium–rare-earth ores by atomic emission spectrometry and inductively coupled plasma mass spectrometry, two procedures are developed for sample preparation based on autoclave decomposition and flux fusion. Autoclave decomposition is carried out in a mixture of HF and HNO3 at a temperature of up to 220°C and a pressure of up to 160 atm using a developed system with resistive heating. Subsequent evaporation to dry salts ensures the removal of F– ions and silicon as SiF4. The residue is dissolved in a mixture of HCl and H2O2 at 160°C under elevated pressure. The resulting solutions (10% with respect to HCl with the addition of H2O2) are diluted before measurements. The dissolution process is monitored for each sample using stable highly enriched isotopes of 91Zr, 100Mo, 149Sm, and 178Hf. The second procedure is based on fusing samples with a mixture of Na2CO3 and Na2B4O7 at 1050°C in a muffle furnace and dissolving the resulting melt in a mixture of HCl and H2O2. The procedures were tested using the national (NFS-23) and foreign standard samples of composition (OREAS-462, 463, 464, 465, Australia) and real samples of niobium–rare-earth ores.
364-373
Effect of the Nature of a Quaternary Ammonium Salt and the Addition of a Neutral Carrier on Analytical Characteristics of Sulfate-Selective Electrodes
Abstract
A film polyvinyl chloride sulfate-selective electrode based on the sterically accessible higher quaternary ammonium salt, 3,4,5-tris(dodecyloxy)benzyl(oxyethyl)3trimethylammonium chloride, using 1-bromonapthalene as a plasticizer and heptyl p-trifluoroacetylbenzoate as a solvating agent was developed. The limit of detection of the electrode was 6.7 × 10−7 M, lifetime was 1 month, and the slope of the electrode function was 27 mV/decade. The electrode is selective in the presence of interfering Cl−, C2O4−, Br−, and NO3−ions. The interference of carbonate ions was eliminated by maintaining pH at 3.2 ± 0.1. Based on IR spectroscopic and potentiometric studies, it is most likely that the solvation of sulfate ions with heptyl p-trifluoroacetylbenzoate occurs through interaction with the trifluoroacetyl carbonyl carbon atom rather than with hydroxyl groups of the hydrate form.
374-382
Single-Walled Carbon Nanotubes Functionalized with N-(6-aminohexyl) Carboxamide as Ionophore for Sensing Silver Ions
Abstract
In this work; we constructed a silver ion-selective electrode based on N-(6-aminohexyl) carboxamide functionalized single-walled carbon nanotubes (NAHAFSWCN) as an ionophore. The selectivity constant of a number of cations was measured using silver ion selective electrode. Optimal pH was between 3 and 6 and the upper and lower detection limits of the designed electrode were 1.2 × 10–2 and 8 × 10–7 M. The electrode showed a Nernstian response over a silver ion concentration range of 1 × 10–6 to 1 × 10–2 M with a slope of 59.1 ± 0.5 mV/decade. The response time of the electrode was less than 18 s and its effective lifetime was 3 months. The isothermal temperature coefficient of the electrode dE°/dT was determined as 0.00011 V/grad. Thermodynamic functions such as ΔS°, ΔH° and ΔG° were obtained by calculating the thermal coefficient of the electrode.
383-389
Selective Voltammetric and Flow-Injection Determination of Guanosine and Adenosine at a Glassy Carbon Electrode Modified with a Ruthenium Hexachlororuthenate Film
Abstract
An inorganic film of ruthenium hexachlororuthenate (RuRuCl6), deposited on the surface of a glassy carbon electrode, exhibits electrocatalytic activity in the oxidation of purine nucleosides, such as guanosine and adenosine. Appropriate operating conditions are found for fabricating a polymer film on the surface of glassy carbon and for recording the maximum electrocatalytic current for the modified electrode. A method for the selective voltammetric determination of guanosine and adenosine in their simultaneous presence at an electrode modified by a RuRuCl6 film is developed. A procedure is proposed for the amperometric detection of purine nucleosides with this modified electrode under the conditions of flow-injection analysis. The linear dependence of the analytical signal on the concentration of guanosine and adenosine is observed up to 5 × 10–6 M in the stationary mode and up to 5 × 10–7 M in the flow system. The proposed method for the selective determination of guanosine and adenosine was tested in the analysis of human urine.
390-398