A multicommutated flow system with on-line compensation of the Schlieren effect applied to the spectrophotometric determination of pindolol Original Research Article

A continuous flow methodology for the spectrophotometric determination of pindolol in pharmaceutical preparations following complexation with Fe(III) is described. The reaction is carried out within a multicommutated flow network by employing a binary sampling approach. The Schlieren effect, associated with the pronounced concentration gradients, was compensated by using a carrier solution processed on-line with two alternating solutions. The concentration profiles of the resulting carrier solution and sample plug are similar, a fact that prevents the formation of concentration gradients. Beerʹs law was followed for pindolol concentrations of up to 120 μg ml−1. Results were reproducible (RSD <1.1%, n=10) and in agreement with those obtained by the reference procedure. A sampling rate of 30 samples per hour was attained.