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M. S. Raghu, K. Basavaiah, K. N. Prashanth and K. B. Vinay
Iodometric
determination of milligram and microgram amounts of levocetirizine in
pharmaceuticals
Abstract
Four
simple, selective and sensitive methods are described for the determination of
levocetirizine dihydrochloride (LCT) in bulk drug and in tablets. The methods
exploit the well-known analytical reaction between iodide and iodate in the
presence of acid solution. Iodide present is oxidized by iodate in an amount
equivalent to the HCl present in LCT to iodine and the liberated iodine is
determined by four different procedures which inturn quantify LCT at varying
detection range and sensitiveness. Two direct titrimetric procedures involve
titration of iodine by thiosulphate either towards starch end point (method A)
or potentiometrically (method B). Both the methods have a reaction
stiochiometry of 1:1 (LCT: liberated iodine) and have quantification ranges of
2–20 mg LCT for method A and method B. The liberated iodine is also measured
spectrophotometrically at 350 nm (method C) or the iodine-starch complex
measured at 570 nm (method D). In both the methods, the absorbance is found to
be linearly dependent on the concentration of iodine which in turn is related
to LCT concentration. The calibration curves are linear over 5–40 and 1.25–12.5
µg ml–1 LCT for method C and method D, respectively. The calculated
molar absorptivity and Sandel sensitivity values are 1.0´104 l mol–1 cm–1
and 0.0435 µg cm–2, respectively for method C, and their respective
values for method D are 2.9´104
l mol–1 cm–1 and 0.0156 µg cm–2. The intra-day
and inter-day accuracy and precision studies were carried according to the ICH
guidelines. The method was successfully applied to the analysis of two brands
of tablets LCT. The accuracy was also checked by placebo blank and synthetic
mixture analyses besides recovery study via standard addition procedure.
Key words: spectrophotometry, levocetirizine, titrimetry, Potentiometry,
pharmaceuticals.
Copyright (C) Chemistry Dept., Moscow State University, 2002
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