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Abstract:The Slovak-Czech spirit distilled from Sorbus domestica was analyzed by GCxGC with headspace solid phase microextraction and liquid-liquid extraction. Two column combinations, nonpolar × medium-polar and polar × medium-polar were tested. The second column setup provided more exploited 2D separation space with better distribution of peaks in chromatogram. Effects of the first column on the elution order of γ-lactones, benzyl esters, and unsaturated aldehydes in the second separation were observed. More than 500 compounds were detected; nearly 100 were confirmed with standards.

In present paper, a miniaturized boron-doped diamond electrode (BDDE) was for the first time used as a reliable electrochemical sensor within the novel voltammetric protocol for the rapid and simple determination of dipyridamole (DIP). Cyclic voltammetric studies uncovered that the electrochemical oxidation of DIP was shown to be irreversible and diffusion-controlled process with single and well-developed signal at a potential of +0.45 V in Britton-Robinson buffer at pH 3.0. Using the suitable experimental conditions, the linearity for DIP determination was observed in the concentration ranges of 0.1−5.0 μM and 0.1−6.0 μM with the corresponding limits of detection of 40 nM and 60 nM as well as the intra-day repeatability with relative standard deviation below 5% for differential pulse and square-wave voltammetry, respectively. This protocol was successfully applied to the determination of DIP in pharmaceutical tablets with result in good compliance with that declared by the producer. Biological pertinence of the developed procedure was presented by analysis of model human urine samples with adequate recoveries. The proposed protocol with a miniaturized BDDE could represent an effective and alternative analytical implement for DIP determination instead of commonly used toxic mercury and chemically-modified electrodes in previously published methods.

A novel voltammetric method of local anesthetics such as lidocaine, trimecaine and mepivacaine determination has been developed. The proposed method was based on the obtaining of anesthetic N‐oxides in oxidation reaction with futher reduction of reaction product. Experimental conditions affecting quantitative yield of anesthetic N‐oxides such as oxidation time, oxidant concentration and temperature were studied. This assay was found to be linear (R=0.999) over a concentration range n⋅10−6–5 ⋅ 10−5 mol L−1. Calculated LOD and LOQ were found to be 0.38 and 1.14 μg mL−1 respectively. Sensitivity of presented method is comparable with that of chromatographic method. Overall, the developed method exhibited good selectivity towards components of pharmaceuticals and biological fluids. The proposed method was successfully applied to the analysis of studied anesthetics in different pharmaceutical samples.

The voltammetric behaviour of Ga(III) complexes with o,o'-dihydroxysubstituted azo dyes (eriochrome red B (ERB), eriochrome black T (EBT), calcon (Calc), and kalces (Klc)) was investigated using cyclic linear-sweep voltammetry. Two new reduction peaks caused by reduction of the Ga(III)-azo dye complex compounds were registered on the voltammograms. The effect of pH, the concentration of azo dye and Ga(III) ions, and the sweep rate on the peak current was studied. The peak current changed linearly with increasing gallium concentration. New methods were proposed for the determination of metal ions. The detection limits were 2.0×10-7 M for the Ga(III)-ERB complex, 1.0×10-6 M for the Ga(III)-EBT and Ga(III)-Calc systems, 5.3×10-7 M for the Ga(III)-Klc complex based on the first peak and 9.1×10-7 M for the same system but based on the second peak. The proposed methods were tested on the determination of gallium in intermetallic compounds of the Zn-Ga and Sm-Ga systems and in a Gd 3 Sc 2 Ga 3 O luminophore.