2-PHASE PHOTOMETRIC ION-PAIR TITRATION OF CHLORPHENIRAMINE MALEATE INTABLET, POWDER AND INJECTION FORM USING METHYL-ORANGE AS THE TITRANT

Chlorpheniramine maleate (CPM) in tablet (CPM-T), powder (CPM-P) and i njection (CPM-I) forms according to The Japanese Pharmacopoeia Thirtee nth Edition (JP-XIII) was determined by the two-phase photometric ion- pair titration (TPPIT) method using Methyl Orange (MO) as the titrant. Ten mi of a buffer solution (pH 5) and 40 mi of dichloromethane (DCM) were added to a sample containing about 0.5 mg CPM and titrate in a 1 x 10(-3) M MO standard solution; the solution was then stirred for 2 minutes. After the solution was separated into two layers, the absorba nce of the DCM layer was measured at 425 nm. By repeating this operati on, a titration curve was prepared and the titration end point was obt ained. The amount of CPM was calculated, and compared with that determ ined by the JP-XIII method. No significant difference was found in the accuracy between the two methods. Therefore, the TPPIT method is a us eful method for the determination of CPM.