A tricyanovinyl azobenzene dye used for the optical detection of amines via a chemical reaction in polymer layers

The reactive tricyanovinyl group of the lipophilic dye 4-N,N-dioctylamino-4'-tricyanovinylazobenzene dissolved in plasticised PVC interacts with aqueous amines and gives colour changes from blue to orange. Since the conversion of the tricyanovinyl into an 1-amino-2,2-dicyanovinyl group is irreversible, the determination of analyte concentrations has to be performed via kinetic evaluation. The sensitivity of the chemically reactive dye in the polymer layer is highest for lipophilic primary amines and, in the case of aqueous I-propylamine, covers the range from 0.5 to 4 mM with a limit of detection of 0.1 mM. The maximum signal changes of the chromoreactand in the polymer layer are observed at 642 nm making the probe compatible with cheap light sources and detectors. (C) 2003 Elsevier Ltd. All rights reserved.