Flow injection extraction applied to dissolution rate studies of felodipine tablets.

A flow injection analysis (FIA) extraction method has been developed for the analysis of felodipine tablets in connection with dissolution rate testing. The water-soluble oxidation product of felodipine, a pyridine derivative, was extracted into chloroform and measured at 275 nm spectrophotometrically. The FIA-extraction method has been compared with the present liquid chromatographic (LC) method. The sampling rate for the FIA-extraction (60 samples h-1) is 5 times higher than for the LC method. The FIA-extraction method has a standard deviation of 1% for both standards and samples which is the same as for the LC method.