Composites: A novel alternative to construct solid state Ag/AgCl reference electrodes

An Ag/AgCl solid-state reference electrode is developed by means of a graphiteAgClSilver dag-epoxy resin composite. The response of the composite reference electrode (CRE) to chloride ions is evaluated; a linear non-nernstian response is observed associated to the following equation E = ?15.15 (1.10) ? 44.05 (0.38) log[Cl?]. Comparing the CRE's response potential versus a saturated commercial Ag/AgCl reference in KCl 0.1 M, a mean of 40.7 0.4 mV of the distribution of potential versus time data is observed over a period of 1 h. The performance of the CRE as reference for a glass membrane electrode by means of direct pH measurements and quantitative determination of acids by acidbase titrations is evaluated obtaining statistically stable, precise and exact results compared with those obtained using a combined glass electrode. The typical cylindrical configuration of the CRE is changed to adapt it to a FIA system for the determination of ammonium ion, obtaining a sensitivity 50.30 0.26 mV/log[NH4+] and a linear range 8.5 × 10?5 to 0.1 M, which are analytical parameters statistically equivalent to those presented by the classical determination system.