Extraction-frequencymetric method. A new measurement technique for determination of micro amounts of chlorpheniramine

A new measurement technique has been proposed and applied to the determination of chlorpheniramine as an example of its application. It is based on the extraction of free chlorpheniramine into carbon tetrachloride after neutralization with a basic agent, followed by measurement of the frequency change of the specially designed ring-coated piezoelectric sensor after evaporation of the extractant from the crystal surface. The frequency change is proportional to the chlorpheniramine amount in the range 0.025-1.2 microgram. The method has been applied to the determination of chlorpheniramine maleate in pharmaceutical preparations.