The sustainable and green chemistry principles enable scientists to protect and benefit the economy, people and the planet by finding creative and innovative ways to reduce waste, conserve energy, and discover replacements for hazardous substances. In this work, an environmentally friendly ion selective electrode (ISE) potentiometric method was developed for the determination of cinchocaine hydrochloride (CIN) in presence of its degradation products either in bulk powder or in its combined pharmaceutical formulation with betametahsone valerate. Two novel CIN-selective electrodes were fabricated and evaluated. The fabrication of electrodes was based on sodium tetrakis [3,5-bis (trifluoromethyl)phenyl]borate as a cationic exchanger in a PVC matrix with 2-nitrophenyl octyl ether (2-NPOE) as a plasticizer and using 2-hydroxy propyl-β-cyclodextrin (2-HP β-CD) as an ionophore. A comparative study was conducted using two designed CIN-selective electrodes; a conventional liquid inner contact, sensor 1, and a glassy carbon solid contact electrode, sensor 2. Sensor 1 has a linear dynamic range of 3.0 × 10 −5 mol L −1 to 1.0 × 10 −2 mol L −1 , with a Nernstian slope of 54.89 mV/decade and a detection limit of 5.01 × 10 −6 mol/L. Sensor 2 shows linearity over the concentration range of 1.0 × 10 −5 mol L −1 to 1.0 × 10 −2 mol L −1 , with a Nernstian slope of 57.01 mV/decade and a limit of detection of 2.51 × 10 −6 mol L −1 which is much improved as a result of diminishing ion fluxes in this solid contact ion-selective electrode. The present electrodes show clear selectivity for CIN from several inorganic, structurally related organic molecules, sugars, co-formulated drug, some common drug excipients and its degradation products. The results obtained by the proposed sensors were statistically analyzed and compared with those obtained by official method. No significant difference for either accuracy or precision was observed.
The formation of metal chelates with various ligands may lead to the production of fluorescent chelates or enhance the fluorescence of the chelating agent. This paper describes two sensitive, selective and computer-solved methods, namely, zero order (SF) and second-derivative synchronous spectrofluorimetry (SDSFS) for nano-quantitation of two carbapenems; meropenem (MP) and ertapenem (EP). The methods are based on the chelation of MP with Tb and EP with Zr in buffered organic medium at pH 4.0 to produce fluorescent chelates. In the zero order method, the relative synchronous fluorescence intensity is measured at 327.0 nm at Δλ = 70.0 and 100.0 nm for MP and EP, respectively. The second method utilizes a second-derivative technique to enhance the method selectivity and emphasize a stability-indicating approach. The peak amplitudes ( D) of the second-derivative synchronous spectra were estimated to be 333.06 and 330.06 nm for MP and EP, respectively. The proposed synchronous spectrofluorimetric methods were validated according to the International Conference on Harmonization (ICH) guidelines and applied successfully for the analysis of MP and EP in pure forms, pharmaceutical vials and in synthetic mixtures with different degradants of both drugs. Under optimum conditions, the mole-ratio method was applied and the co-ordination ratios of MP-Tb and EP-Zr chelates were found to be 1:1 and 1:3. The formation constants for the chelation complexes were evaluated using the Benesi-Hildebrand's equation; the free energy change (ΔG) was also calculated. The results indicated that EP-Zr was more stable than the MP-Tb chelate. Moreover, the developed methods were found to be selective and inexpensive for quantitative determination of both drugs in quality control laboratories at nano-levels.
Antibiotics determination plays a major role in minimizing antimicrobial resistance starting from quality control of pharmaceutical formulations to therapeutic drug monitoring. Green modified glassy carbon electrode has been developed for determination of tedizolid phosphate; new antibiotic prodrug; in presence of its active metabolite. The graphene transducer interlayer, dispersed with PVC, improved the electrode stability and standard potential reproducibility. Graphene hydrophobicity prevented the water layer formation between the sensing layers that decreased the potential drift down to 267 μV h−1. Electrochemical impedance showed a low resistance value for graphene containing sensor due to its high electron transfer ability.
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