Spectrophotometric determination of metronidazole and tinidazole via charge transfer complexation using chloranilic acid

Abstract

A new spectrophotometric method was developed for the determination of two important nitroimidazoles; metronidazole (MZ) and tinidazole (TZ). The method was based on the charge-transfer (CT) complexation reaction of reduced forms of metronidazole and tinidazole as n-electron donors and chloranilic acid (CAA) as ʌ-electron acceptor to form a purple-colored complex with a new absorption band at 520 nm which was adopted as the analytical wavelength. Molar absorptivities of 2.741 u 10 2 L M -1 cm -1 and 2.681 u 10 2 L M -1 cm -1 were obtained for MZ and TZ, respectively. Optimization of reducing agent and time of reduction revealed the superiority of metal hydrides over reducing metals. Reduction of MZ and TZ was completed at 30 °C within 10 min. Optimizations of temperature and time for the complexation reaction revealed that the reaction was completed at 30 °C within 5 min. A 60:40 mixture of 1,4-dioxane:acetonitrile was found to be the best diluting solvent for optimal detector response. The complexes were stable at room temperatures for weeks. Beer's law was observed in the concentration of 5-40 μg ml (MZ) and 4.8-79.2 μg ml -1 (TZ) with low limits of detection of 1.88 and 0.74 μg ml -1 , respectively. Overall recoveries of MZ and TZ from quality control samples were 103.19 ± 2.05 (%RSD = 1.99, n = 12) and 101.63 ± 1.41 (%RSD = 1.39) over three days. There was no interference from commonly utilized tablet excipients. No significant difference existed between the results of the new method and the BP titrimetric procedures (p > 0.05). The new CT procedure described in this paper is simple, fast, convenient, accurate and precise and has the novelty of carrying out the reactions at room temperature compared to previously described procedures.The new method could be adopted as an alternative procedure for the quality assessment of MZ and TZ in bulk and dosage forms.

Voltammetric determination of tinidazole in pharmaceutical tablets using carbon paste electrode

“…Analytical methods including HPLC [14][15][16][17] with different detectors and spectrophotometry [7,[18][19][20][21][22][23] have been reported on the determination of tinidazole in tablet, urine, and biological fluids. Since most of the conventional methods reported need trained personnel to operate, are expensive and not environmentally friendly, the development of electrochemical methods which are selective, sensitive, cheap and environmentally friendly is central.…”

Simultaneous spectrophotometric determination of trimethoprim and sulphamethoxazole following charge-transfer complexation with chloranilic acid

“…This is quite the reverse of the effect produced with TMP. Thus HSMZ-CAA obeyed the typical mechanism of CT reactions where increasing temperature Simultaneous spectrophotometric determination of trimethoprim and sulphamethoxazole breaks down the product of the complexation (Adegoke et al, 2010(Adegoke et al, , 2011.…”

“…b Estimated from Benesi-Hildebrand plot. absorbance values compared to TMP-CAA where acetonitrile-dioxane mixture was optimal. Acetonitrile and 1,4-dioxane have found a regular use in most CAA procedures as the solvents are known to stabilize the CT complexes resulting from CAA and other charge donors (Adegoke et al, 2010;Onah and Odeiani, 2002).…”

Trichloroisocyanuric acid and NaNO2 mediated nitration of indoles under acid-free and Vilsmeier–Haack conditions: synthesis and kinetic study

“…Review article published by Katrizky et al [16] provided excellent bibliography on the direct mono nitration of wide varieties of heterocyclic compounds like furans, pyrroles, thiophenes, pyrazoles, imidazoles, isoxazoles and thiazoles using nitric acid/trifluoroacetic anhydride as nitrating agent. Adegoke et al [17] accomplished spectrophotometric determination of metronidazole and tinidazole via charge transfer complexation using chloranilic acid. Mukherjee and Boshaff [18] explored that nitroimidazoles could be effectively used for the treatment of TB.…”