Aconductometricnitratebiosensorbasedonmethylviologen/Nafion/nitratereductase(NR)interdigitatedelectrodeforheavymetaldeterminationwasproposed.TheactivityofNR(EC1.6.6.2)fromAspergillusniger(A.niger)wasassayedasafunctionofmetalconcentrationinthepresenceofCu2+,Zn2+,Cd2+andPb2+.Parametersinfluencingtheperformanceofthebiosensorwereoptimizedfortheapplicationofitintheinhibitiondeterminationofheavymetalions.DetectionlimitsforCu2+,Zn2+,Cd2+andPb2+wereabout0.05,0.5,0.1and1.0μmol/L,respectively.TheresultsshowthatNRactivitycouldnotberegainedafterexposuretoCu2+,butcouldbepartiallyrecoveredafterexposuretoZn2+,Pb2+andCd2+.
