Polymers as transducer supports

Protons in water (pH) Polystyrene bearing amino groups [33] 

Ions (ionic strength) Sulfonated polystyrene, sulfonated dextran [34] 

Water in organic liquids Polystyrene bearing quaternary ammonium groups [35] 

Hydrocarbons in water Poly (methyl trifluoropropyl siloxane), poly (dimethyl siloxane), poly(styrene-co-butyl methacrylate) [36, 37] 

A large number of optodes developed for the selective detection of inorganic anions and cations, so-called ion-selective optodes (see Table 13.2), consist of polymer membranes that contain transducers. The latter are mostly physically admixed, but in some cases they are covalently bound to the polymer matrix. Most of these optodes [7, 8] are based on poly(vinyl chloride), plasticized with DOS, BBPA, DOP, o-NPOE or other plasticizers (see Chart 13.3). Typically, membranes are composed of 33 wt.% PVC, 66 wt% plasticizer, and 1 wt% ionophore (analyte-complexing agent) and lipophilic salt (ion-exchanger). Other polymers occasionally employed in hydrophobic optodes include polysiloxanes and poly(vi- 

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