Test preparation— Dissolve about 200 mg of Chlorpheniramine Maleate in 5 mL of methylene chloride, and mix.

Chromatographic system (see Chromatography 621)— The gas chromatograph is equipped with a flame-ionization detector and a 1.2-m × 4-mm glass column containing 3% phase G3 on support S1AB. The column temperature is maintained at about 190, and the injection port and detector temperatures are both maintained at about 250. The carrier gas is dry helium, flowing at a rate adjusted to obtain a retention time of 4 to 5 minutes for the main peak. Chromatograph the Test preparation, record the chromatogram, and determine the peak area as directed for Procedure: the tailing factor for the chlorpheniramine maleate peak is not more than 1.8.

Procedure— Inject a volume (about 1 µL) of the Test preparation into the chromatograph. Record the chromatogram for a total time of not less than twice the retention time of the chlorpheniramine peak, and measure the areas of the peaks. The total relative area of all extraneous peaks (except that of the solvent peak and maleic acid, if observed) does not exceed 2.0%.