Fast determination of paracetamol by using a very simple photometric flow-through sensing device

A simple flow-through UV optosensing device was developed:for the determina tion of paracetamol based on its transient retention and concentration on a suitable active solid support (Sephadex QAE A-25 anion-exchange resin) pac ked in the flow cell and the continuous monitoring of its native absorbance on the solid phase at 264 nm. The sample was injected into a 0.08-M NaCl c arrier stream at pH 11.0 by using a simple monochannel FIA manifold. After developing the analytical signal, paracetamol was desorbed from the solid s upport by the carrier solution itself. A very good linear response was foun d in the concentration range 0.5-8.0 mu g ml(-1) with a RSD (%) of 1.24, a detection limit of 0.022 mu g ml(-1) and a sampling rate of 40 h(-1). A str ong increase in sensitivity as well as a very much higher selectivity were achieved as compared with the conventional flow injection method as a conse quence of the separation of the analyte from the sample plug and its retent ion on the active solid support placed in the detection area. Applicability of the proposed sensor to direct determination of paracetamol in pharmaceu ticals (to solve the sample being the only treatment) was successfully demo nstrated. (C) 2000 Elsevier Science B.V. All rights reserved.