Optical fibre reflectance sensors for the detection of heavy metal ions based on immobilised Br-PADAP

Optical fibre based reflectance sensors for the detection of heavy metal ions have been developed based on the use of the immobilised reagent Br-PADAP. Two methods of immobilisation, namely physical adsorption and membrane entrapment, have been employed and their relative merits have been discussed. Br-PADAP immobilised onto XAD-4 shows a reproducible and reversible response to heavy metal ions and a good limit of detection (31 ppb for Zn(II) with an analysis time of 6 min). Br-PADAP/PVC membranes show fairly quick and reproducible responses, but are irreversible. Br-PADAP/XAD-4 is proposed as a suitable reagent phase for use in a multi-metal ion sensor. (C) 1998 Elsevier Science S.A. All rights reserved.