Voltammetric behavior and determination of the macrolide antibiotics azithromycin, clarithromycin and roxithromycin at a renewable silver – amalgam film electrode

Abstract

The renewable silver-amalgam film electrode (Hg(Ag)FE) was applied for voltammetric characterization and determination of semi-synthetic macrolide antibiotics azithromycin (AZI), clarithromycin (CLA) and roxithromycin (ROX) in the Britton-Robinson buffer as supporting electrolyte ranging the pH from 4.0 to 11.9. All three macrolides showed reduction signals in fairly negative potential range.During direct cathodic square wave voltammetric (SWV) investigations conducted over the potential range from À0.75 V to À2.00 V vs SCE, either one or two reduction peaks were obtained in the potential range from À1.5 to À1.9 V. The shapes and intensities of the signals depend on the applied pH values in wider pH ranges. For analytical purposes concerning the development of direct cathodic SWV and adsorptive stripping SWV (SW-AdSV) methods the neutral and slightly alkaline media were suitable as pH 7.2, pH 7.4 and pH 7.0 for AZI, CLA and ROX, respectively. Based on the cyclic voltammograms recorded at these pH values, adsorption-controlled electrode kinetics process can be proposed for all three macrolides. Furthermore, the water suppressed 1 H NMR measurements in the pH range between 6.0 and 10.5 indicated that the macrolide molecules at the optimal analytical conditions are predominantly in protonated form via their tertiary amino groups which supported in all three cases their adsorption on the appropriately polarized Hg(Ag)FE electrode. The optimized direct cathodic SWV methods showed good linearity in concentration ranges 4.81-23.3 mg mL À1 , 1.96-28.6 mg mL À1 and 1.48-25.9 mg mL À1 for AZI, CLA and ROX, respectively. The development of the SW-AdSV methods resulted in the linear responses at lower concentration ranges as 1.0-2.46 mg mL À1, 0.05-0.99 mg mL À1 and 0.10-0.99 mg mL À1 , for AZI, CLA and ROX, respectively. The relative standard deviation for all developed methods was not higher than 1.0% except the SWV method for AZI with 4.7%. In the case of all three investigated macrolide antibiotics the protonated form of the tertiary amino group(s) at appropriate accumulation potential and time favored the adsorption of the ionic form of the target molecules offering the opportunity for the development of SW-AdSV methods for their trace level analysis on Hg(Ag)FE. Optimized SW-AdSV method was applied for determination of ROX in pharmaceutical preparation Runac

Equilibrium and kinetic studies of the adsorption of antibiotics from aqueous solutions onto powdered zeolites

“…For AZM, the adsorption is maximum at the pH value near to the molecule pKa (8.7) on both zeolites. At acid pH conditions, AZM occur predominantly in their protonated form via the tertiary amino group ([eNH(CH 3 ) 2 ]) (Vajdle et al, 2017). Similar to SMX, the adsorption mechanism must be attributed to the electrostatic interaction and H-bonding between the ionized and unionized molecules of AZM and ≡SieOgroups on the zeolite surface.…”

Additional Studies on the Electrochemical Behaviour of Three Macrolides on Pt and Carbon Based Electrodes

“…Concerning the mechanism of ERT, CLA, AZT oxidation on different working electrodes, there have been already some initial studies [33,44,45], however additional experimental proof was brought in this work. For this purpose, the same measurements were done with five different simpler organic molecules; cyclohexanol, benzaldehyde, aniline, ninhydrine, and 4-dimeth-ylaminobenzaldehyde, as they have functional groups expected to be electrochemically active just as the macrolides under consideration.…”

“…Identification and quantification of macrolides has mostly been performed using high-performance liquid chromatography-tandem mass spectroscopy with a modified solid phase extraction pre-treatment step [25,26]. Moreover, electroanalytical methods based on using different electrochemical (bio) sensors were developed in order to improve selectivity and sensitivity of the macrolide quantification [27][28][29][30][31][32][33]. One of the most used materials as working electrode for important molecules detection and quantification is carbon.…”

Determination of Six Macrolide Antibiotics in Chicken Sample by Liquid Chromatography-Tandem Mass Spectrometry Based on Solid Phase Extraction

“…Recently, with the development of analytical instruments, various analytical methods have been gradually developed to determine the trace drug residues in complex matrices, including capillary electrophoresis (CE) [12–14], enzyme-linked immunosorbent assay (ELISA) [15], thin-layer chromatography (TLC) [16], voltammetric measurements [17], gas chromatography coupled to mass spectrometry (GC-MS) [18, 19], high-performance liquid chromatography (HPLC) [20–22], and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) [2, 23–27]. Among these analytical methods, LC-MS/MS appears to be acknowledged as the most useful and authoritative methods for the quantification of MACs in complex matrices, due to its high sensitivity and good specificity [24, 26].…”