DEVELOPMENT OF A SENSOR CARD WITH INTEGRATED REFERENCE FOR THE DETECTION OF NITRATE

Based on thick-film technology a complete nitrate sensor card is desig ned and investigated. In this potentiometric device, the transducer co nsists of an epoxy resin substrate, two different conductive layers an d an epoxy resin encapsulation. The receptor is a PVC membrane with TD MA-NO3 (tridodecylmethylammonium nitrate) as the anion exchanger and 2 -NPOE (2-nitrophenyl octyl ether) as plasticizer mounted directly onto the surface of a silver layer. The reference electrode is introduced onto the same substrate by deposition of a hydrogel which contains a 0 .2 M KCl solution. To prevent the solution from leaching out,the hydro gel is covered by a photopolymerized epoxy resin with a small opening for the liquid junction.