Multi-pumping flow system for spectrophotometric determination of bromhexine

Abstract

A novel flow-based procedure involving the multi-pumping approach was developed for the spectrophotometric determination of bromhexine in pharmaceutical preparations. The method is based on reaction with 3-methyl-2-benzothiazolinone hydrazone (MBTH) and Ce(IV). Several solenoid micro-pumps are present in the manifold in order to provide improved system control. Critical tasks in continuous flow analysis, sample–reagent introduction and solution propelling, are then efficiently carried out. Moreover, the pulsed flow inherent to the mini-pumps ensures good mixing conditions, thus improving the reaction zone homogenisation. This aspect becomes particularly attractive for the implementation of analytical procedures involving several consecutive reactions as it happens with the proposed procedure. Linear calibration plots ( r>0.995, n=6) were obtained for bromhexine concentrations up to 400 mg l −1. Detection limit was 2 mg l −1 and the sampling rate was about 45 samples h −1. Results are precise (R.S.D.<1.5%; n=10) and in agreement with those furnished by the reference procedure involving a potentiometric titration.