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

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. Beer's law was followed for pindolol concentrations of up to 120 mu g 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. (C) 1998 Elsevier Science B.V.