A new approach to the spectrophotometric determination of metronidazole and tinidazole using p-dimethylaminobenzaldehyde
A new approach to the spectrophotometric determination of metronidazole (MZ) and tinidazole (TZ) has been developed. The procedure involves coupling of diazotized nitroimidazoles with p-dimethylaminobenzaldehyde (DMAB) to form a greenish-yellow solution. Optimal temperature and time were 0 °C (iced) and 3 minutes for diazotization and 30 °C and 2 minutes for coupling for both MZ and TZ. Coloured adducts of MZ and TZ showed shoulders at 406 nm and 404 nm, respectively, which were selected as analytical wavelengths. The reaction with p-DMAB occurred in a 1:1 mole ratio. Beer's law was obeyed within the 4.8-76.8 μg mL-1 concentration range with low limits of detection. The azo adducts were stable for over a week. Molar absorptivities were 1.10 × 103 (MZ) and 1.30 × 103 L mol-1 cm-1 (TZ). Overall recoveries of MZ and TZ from quality control samples were 103.2 ± 1.3 and 101.9 ± 1.3% over three days. There was no interference from commonly utilized tablet excipients. No significant difference was obtained between the results of the new method and the BP titrimetric procedures. The azo approach using the p-dimethylaminobenzaldehyde procedure described in this paper is simple, fast, accurate and precise. It is the first application of DMAB as a coupling component in the diazo coupling reaction.
A. R. Katritzky, E. F. V. Scriven, S. Majumder, R. G. Akhmedova, N. G. Akhmedov and A. V. Vakulenko, Direct nitration of five membered heterocycles, ARKIVOC iii (2005) 179-191.
A. Gennaro, Remington's Pharmaceutical Sciences, 18th ed., Mack Publishing Co., Easton 1993, pp. 1228-1230.
R. J. Knox, R. C. Knight and D. I. Edwards, Interaction of nitroimidazole drugs with DNA in vitro: structure-activity relationships, Br. J. Cancer 44 (1981) 741-745.
British Pharmacopoeia, Her Majesty's Stationery Office, London 2001.
A. Z. A. Zuhri, S. I. Al-Khalil and M. S. Suleiman, Electrochemical reduction of metronidazole and its determination in pharmaceutical dosage forms by DC polarography, Anal. Lett. 19 (1986) 453-459.
G. O. El-Sayed, Polarographic determination of metronidazole in pharmaceutical formulations and urine, Microchem. J. 55 (1997) 110-114; DOI:10.1006/mchj.1996.1307.
K. B. Mustapha, M. T. Odunola, M. Garba and O. Obodozie, Rapid, cost-effective liquid chromatograghic method for the determination of metronidazole in biological fluids, Afr. J. Biotech. 5 (2006) 1188-1190.
S. S. Simoes, P. M. Everado, N. G. Everado, S. L. Wellington, N. T. M. Pablo, C. U. A. Mario, C. S. Edvan and B. N. Valberes, Flow injection determination of metronidazole through spectrophotometric measurement of the nitrite ion produced upon alkaline hydrolysis, J. Braz. Chem. Soc. 17 (2006) 609-613; DOI: 10.1590/S0103-50532006000300028.
B. H. Ahmed and J. O. Onah, Colorimetric determination of chloramphenicol and metronidazole in pharmaceutical formulations after Schiff-base formation with vanillin and anisaldehyde, Global J. Pure Appl. Sci. 9 (2003) 359-364.
A. Rehman, A. S. Ijaz and A. Raz Spectrophotometric determination of metronidazole in pharmaceutical dosage forms using p-benzoquinone, J. Iran. Chem. Soc. 2 (2005) 197-202.
C. S. P. Sastry, M. Aruna and A. R. M. Rao, Spectrophotometric determination of some antiamoebic and anthelmintic drugs with metol and chromium (VI), Talanta 35 (1988) 23-26; DOI: 10.1016/0039-9140(88)80006-7.
L. Lopez Martine, F. J. Luna Hernandez and P. L. Lopez Alba, Simple spectrophotometric determination of tinidazole in formulation and serum, Anal. Chim. Acta 340 (1997) 241-244; DOI: 10.1016/S0003-2670(96)00508-9.
C. V. Prasad, V. Sripriya, R. N. Saha and P. Parimoo, Simultaneous determination of tinidazole, furazolidone and diloxanide furoate in a combined tablet preparation by second-derivative spectrophotometry, J. Pharm. Biomed. Anal. 21 (1999) 961-968; DOI: 10.1016/S0731-7085(99)00190-9.
N. D. Dinesh, P. Nagaraja and K. S. Rangappa, A sensitive spectrophotometric assay for tinidazole and metronidazole using a Pd-C and formic acid reduction system, Turk. J. Chem. 28 (2004) 335-344
P. Nagaraja, K. R. Sunitha, R. A. Vasantha and H. S. Yathirajan, Spectrophotometric determination of metronidazole and tinidazole in pharmaceutical preparations, J. Pharm. Biomed. Anal. 28 (2002) 527-53; DOI: 10.1016/S0731-7085(01)00685-9.
K. Siddappa, M. Mallikarjun, P. T. Reddy and M. Tambe, Spectrophotometric determination of metroniodazole through Schiff's base system using vanillin and PDAB reagents in pharmaceutical preparations, Ecle. Quím. (Sao Paulo) 33 (2008) 41-46; DOI: 10.1590/S0100-46702008000400005.
O. A. Adegoke and C. E. Nwoke, Spectrophotometric determination of hydralazine using p-dimethylaminobenzaldehyde, J. Iran. Chem. Soc. 5 (2008) 316-323.
H. T. Karnes and C. March, Precision, accuracy and data acceptance criteria in biopharmaceutical analysis, Pharm. Res. 10 (1993) 1420-1426.
J. Rose, Advanced Physico-Chemical Experiments, Pitman, London 1964, p. 54.
ICH Topic Q2 (R1), Validation of Analytical Procedures: Text and Methodology (CPMP/ICH/281/95); accessed June 30, 2008.
United States Pharmacopoeia 24/National Formulary 19, US Pharmacopoeial Convention, Rockville 2000, p. 819.