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The electrochemical behavior of tolterodine, an antimuscarinic drug used to treat urge incontinence and overactive bladder, was investigated using cyclic and differential pulse voltammetry at glassy carbon electrode. Electrooxidation of tolterodine proceeds as a complex two-step pH-dependent process. Controlled potential electrolysis of tolterodine solutions was performed at platinum gauze electrode in methanolic, aqueous-methanolic and acetonitrile media. Electrolyzed solutions were analyzed using liquid chromatography with electrospray ionization quadrupole time-of-flight mass spectrometry. 5-Hydroxymethyl tolterodine, the main biologically active metabolite of tolterodine, was identified among monomeric oxidation products. Dimeric products, formed by oxidative coupling of phenoxy radicals, were found in all electrolyzed solutions. The mechanism of the electrochemical oxidation of tolterodine has been proposed. [ABSTRACT FROM AUTHOR]

The electrochemical behavior of 5-hydroxymethyl tolterodine (5-HMT), the active metabolite of antimuscarinic drugs tolterodine and fesoterodine used to treat urge incontinence and overactive bladder, was investigated using cyclic and differential pulse voltammetry at glassy carbon electrode. Electrooxidation of 5-HMT proceeds as a complex pH-dependent process. Controlled potential electrolysis of 5-HMT solutions was performed at platinum gauze electrode in aqueous-methanolic media. Electrolyzed solutions were analyzed using ultra performance liquid chromatography with electrospray ionization quadrupole time-of-flight mass spectrometry. Two main oxidation centers of the studied molecule were located: the p -hydroxybenzyl alcohol group and the tertiary amino group. Oxidation of the first center proceeds in several steps leading to the formation of 5-formyl tolterodine, p -benzoquinone derivative and several dimeric, hydroxylated and methoxylated products depending on pH of the solution and electrode potential. The second center is oxidized preferentially in alkaline media at higher potentials under the hydrolytic cleavage of diisopropylamine and formation of corresponding aldehydes. Mechanism of the electrochemical oxidation of 5-HMT has been proposed. [ABSTRACT FROM AUTHOR]

Objective determination of chili peppers pungency, for which capsaicinoids (CPDs), predominantly capsaicin (CA) and dihydrocapsaicin (DHC) are responsible, belongs to frequently solved tasks in food and medicinal analysis. In this manuscript, application of ex-situ extractive stripping voltammetry (ExSV) utilizing a phospholipid modified glassy carbon electrode is described. The obtained analytical parameters, e.g., linear dynamic range from 3 to 60 mg L−1, limit of detection 2.1 mg L−1, proved to be fully comparable with those achieved using the direct voltammetric method on a polished glassy carbon electrode and reference HPLC/UV. Although the sensitivity of ExSV was slightly lower compared to the direct method, ExSV provided better selectivity to CPDs due to their lipophilic interactions with the phospholipid layer. Hydrophilic components of the chili pepper samples were not extracted into the phospholipid layer and therefore did not interfere. The developed method was tested on the determination of CPDs in different chili peppers: Foxta, Madras Chilli, Habanero, Carolina Reaper, Bird's eye, Bhut Jolokia, Naga Jolokia extract, and Habanero extract. Furthermore, the electrochemical reactions of CPDs in acidic aqueous-methanolic media were characterized using an electrochemical cell hyphenated with mass spectrometer and the main oxidation products were identified. • Phospholipid layer on glassy carbon electrode allows extraction of capsaicinoids. • Extraction improves selectivity and linear range of voltammetric determination. • Ex-situ extraction method was used for determination of chili peppers pungency. • Results accord with HPLC and direct voltammetric method on bare electrode. [ABSTRACT FROM AUTHOR]

Voltammetric behavior of a nonsteroidal anti-inflammatory drug meloxicam was firstly studied using boron doped diamond electrode (BDDE). Two irreversible anodic current peaks were observed in wide pH range at potentials +900 mV and +1400 mV vs. saturated silver-silver chloride electrode. Mechanism of the electrochemical oxidation was proposed and confirmed using high performance liquid chromatography/mass spectrometry analysis of electrolyzed meloxicam solutions. Subsequently, an analytical method for meloxicam determination was developed using differential pulse voltammetry in connection with BDDE. This method provides low limit of detection (5.9 × 10−8 mol L−1) and wide linear dynamic range (2.5 × 10−7–8.5 × 10−5 mol L−1). Finally, model solutions as well as pharmaceutical preparations were successfully analyzed, and the meloxicam content was determined. • Electrochemical behavior of an anti-inflammatory drug meloxicam was firstly studied using boron doped diamond electrode. • Mechanism of the oxidation was proposed using high performance liquid chromatography/mass spectrometry analysis. • Sensitive voltammetric method for MLX determination was developed. • New developed method was successfully applied for pharmaceutical samples analysis. [ABSTRACT FROM AUTHOR]