ION-ASSOCIATION METHOD FOR THE SPECTROPHOTOMETRIC DETERMINATION OF THE ANTITUSSIVE DRUG NOSCAPINE

A simple, sensitive and fairly rapid method for the determination of n oscapine is described, based on the measurement of the absorbance of t he organic soluble ion-association complex formed between the noscapin e monocation and a bulky counter anion. Methyl Orange, Bromothymol Blu e and Bromocresol Green (BCG) were examined as counter ions. The effec t of few solvents, the counter-ion concentration and pH on the extract ion were also investigated. The most suitable system was based on BCG (pH 3.0) with chloroform as the extraction solvent. The use of the oth er counter ions, in conjuction with their respective solvents, was fou nd to be less sensitive. The BCG system exhibits negligible or no inte rference when used for the determination of 38 ppm of noscapine in the presence of several drug excipients, thus lending itself as a possibl e procedure for the determination of this alkaloid in pharmaceutical p reparations.