Stripping Voltammetric Determination of Timolol Drug in Pharmaceuticals and Biological Fluids
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Abstract
A sensitive and reliable stripping voltammetric method was developed to determine timolol drug. This method is based on the adsorptive accumulation of the drug at a hanging mercury drop electrode (HMDE) and then a negative sweep was initiated, which yield a well defined cathodic peak at –850 mV versus (Ag/AgCl) silver reference electrode. To achieve high sensitivity, various experimental and instrumental variables were investigated such as supporting electrolyte, pH, accumulation time and potential, scan rate, frequency, pulse amplitude, convection rate and working electrode area. The monitored adsorptive current was directly proportional to the concentration of timolol and it shows a linear response in the range from 1 × 10<sup>–7</sup> to 1.5 × 10<sup>–6</sup> mol●l<sup>–1</sup> of this drug (correlation coefficient = 0.998) and the detection limit (S/N = 3) is 1.26 × 10<sup>–9</sup> mol●l<sup>–1</sup> at an accumulation time of 30 sec. The developed adsorptive stripping voltammetry (AdSV) procedure shows a good reproducibility, the relative standard deviation RSD% (n = 8) at a concentration level of 1 × 10–6 mol●l<sup>–1</sup> of timolol was 0.13%, whereas the method accuracy was indicated via the mean recovery of 110% ± 1.414%. Possible interferences by several substances usually present in the pharmaceutical formulations have been also evaluated. The applicability of this approach was illustrated by the determination of the drug in pharmaceutical preparation and biological fluids such as serum and urine.
- J. Wang, “Analytical Electrochemistry,” 2nd Edition, VCH Publishers, Inc., New York, 1994, pp. 44-54.
- K. H. Brainina and E. Neyman, “Electroanalytical Stripping Methods,” John Wiley and Sons, New York, 1993, pp. 71-120.
- J. Wang, “Stripping Analysis: Principles, Instrumentation and applications,” VCH Publishers Inc., New York, 1985, pp. 1-160
- R. Kalvoda, “Adsorptive Stripping Voltammetry in Analytical Chemistry II,” Ellis Horwood, New York, 1996.
- J. Wang, “Electroanalytical Techniques in Clinical Chemistry and Laboratory Medicine,” VCH Publishers Inc., New York, 1988, pp. 17-20.
- P. M. Zaitsev, R. M. Salikhdzhanova and N. K. Zaitsev, “Use of Adsorption Voltammetry in Trace Analysis of Inorganic Ions,” Industrial Laboratory, Vol. 65, No. 1, 1999, pp. 1-15.
- A. Z. Abu Zuhri and W. Voelter, “Applications of Adsorptive Stripping Voltammetry for the Trace Analysis of Metals, Pharmaceuticals and Biomolecules,” Fresenius' Journal of Analytical Chemistry, Vol. 360, No. 1, 1998, pp. 1-9. doi:10.1007/s002160050633
- K. H. Brainina, N. A. Malakhova and N. Y. Stojko, “Stripping Voltammetry in Environmental and Food Analysis,” Fresenius' Journal of Analytical Chemistry, Vol. 368, No. 4, 2000, pp. 307-325. doi:10.1007/s002160000525
- N. S. Abdul, S. Afzal, A. M. Sarfraz and R. Abdul, “Adsorptive Stripping Voltammetric Determination of Hydroquinone Using an Electrochemically Pretreated Glassy Carbon Electrode,” Pakistan Journal of Analytical Environmental Chemistry, Vol. 9, No. 2, 2008, pp. 110-117.
- A. H. Alghamdi, “Square-Wave Adsorptive Stripping Voltammetric Determination of an Antihistamine Drug Astemizole,” Chemical Papers, Vol. 62, No. 4, 2002, pp. 339-344.
- J. C. Vire, J. M. Kauffmann and G. J. Patriarche, “Adsorptive Stripping Voltammetry Applied to Drug Analysis: A Powerful Tool,” Journal of Pharmaceutical and Biomedical Analysis, Vol. 7, No. 12, 1998, pp. 1323- 1335.
- M. M. Ghoneim, A. M. Beltagi and A. Radi, “Square- Wave Adsorptive Stripping Voltammetric Determination of the Anti-Inflammatory Drug Lornoxicam,” Analytical Sciences, Vol. 18, No. 2, 2002, p.183.
- O. A. Farghaly, “Adsorptive Stripping Voltammetric Determination of the Antidepressant Drug Sulpiride,” Journal of Pharmaceutical and Biomedical Analysis, Vol. 23, No. 5, October 2000, pp. 783-791. doi:10.1016/S0731-7085(00)00376-9