Screen printed biosensors for detection of nitrates in drinking water

Amperometric screen printed nitrate reductase by Escherichia coli biosensors have been developed to detect nitrate ions. The effects of two different immobilization procedures of NaR and mediator (Azure A and Methyl viologen MV) to increase the performances (response time, sensitivity, stability) of the nitrate sensor have been studied. The best performances were registered by nitrate biosensor developed with a simultaneous cross-linking of enzyme and MV mixed BSA in in satured glutaraldehyde vapour. This biosensor showed the capability to detect nitrate residue levels lower than the European legislation one for a long storage stability (> 36 days) representing an applicable and cheap method for the analysis of nitrate ions in water and food samples.