An Indirect Spectrophotometric Determination of Mesna in Pharmaceuticals and Environmental Samples

Abstract

Two indirect spectrophotometric methods were proposed for the determination of
mesna in pure and pharmaceutical preparations using sodium hypochlorite and two
indicators, methyl orange and congo red. The methods involved addition of a known
excess of sodium hypochlorite to mesna in acidic medium, followed by determination of
residual sodium hypochlorite by reacting with a fixed amount of either methyl orange,
measuring the absorbance at 505nm (method A) or congo red measuring the absorbance
at 605nm (method B). In both methods the amount of sodium hypochlorite reacted
correspond to the amount of mesna and the measured absorbance was found to increase
linearly with the concentration of mesna, which is corroborated by the correlation
coefficient of 0.9996 and 0.9998 for method A and B respectively. The two methods
obey Beer’s law for 0.08-1.6 μg mL -1 and 0.2-2.0 μg mL-1 for method A and B
respectively. The apparent molar absorptivities were calculated to be 1.02×104 and
1.5×103 L mol-1 cm-1 for method A and method B respectively. The limit of detection
(LOD) and quantification (LOQ) were calculated to be 0.016 and0.05μg mL-1 for method
A and 0.048 and 0.15 μg mL-1 for method B. The intra-day and inter-day precision and
accuracy of the two methods were evaluated according to the current ICH guidelines.
Both methods of comparable accuracy(relative error) better than ± 1.8%. and precision of
< 2%. The proposed method was proved to be selective and applied to the determination
of mesna in pharmaceutical preparations and environmental water samples.