Plasticized poly(vinyl chloride) as a permselective barrier membrane for high-selectivity amperometric sensors and biosensors

Abstract

A poly(vinyl chloride) (PVC) membrane system is described for use as a high-selectivity barrier in amperometric sensors and biosensors. Membrane casting and electrode fabrication techniques are presented. The membrane properties, both physical and with respect to permselectivity, are outlined. This new form of homogeneous membrane barrier shows very much greater selectivity for H 2O 2 in oxidase-based enzyme electrodes than any previously reported barrier. Selectivity for the phenolic compounds catechol, hydrocaffeic acid, 4-aminophenol and paracetamol, as model electrochemically active compounds, is described and related to interference from ascorbate and urate; the responses of equimolar catechol: ascrobate and catechol: urate are both 61 500:1, and that of 1 mM catechol: undiluted serum is 60 000:1. Comparative results for a low molecular weight cut-off cellulose acetate layer, commonly employed in amperometric sensors and biosensors for clinical monitoring, demonstrates the superior selectivity of PVC, showing the PVC to have 7 and 180 times greater selectivity for H 2O 2 and paracetamol, respectively, against ascorbate. Biocompatibility is also excellent, with no loss of signal after prolonged exposure to serum.