On Line Determination of Perphenazine Using Flow Injection Analysis

An accurate specific flow injection spectrophotometric method for the determination of perphenazine in the range 50-250 ppm is introduced. In the method, 110 μl of the drug is injected through a stream of 0.2% (w/v) potassium dichromate in 0.25 M sulfuric acid flowing on line as a carrier stream. The drug is oxidized on the flow to the red monocation radical, the peak absorbance of which is monitored at 525 nm. A throughput of up to 300 samples per hour is attained. The mechanism of the reaction is suggested and the method is compared with the United States Pharmacopeia method.