Photochemical-fluorimetric determination of folic acid in a multicommutated flow system

A flow system based on multicommutation was developed for the determination of folic acid by fluorimetry following irradiation by ultraviolet light. The photochemical reaction was carried out in a reaction coil. Insertion of time-controlled sample volumes enabled the determination of a wide range of concentrations without changing the manifold design, which makes it suitable for application to automated dissolution studies. An automated system control selects for each sample, depending on its concentration, the sampling time and therefore the most convenient sample volume. Linear calibration plots were obtained over a concentration range from 0.1 to 40.0 mg l−1 with a relative standard deviation of less than 3% and a sampling rate of about 25 samples per hour.