tA highly sensitive and ultra selective amperometric nitrite sensor was fabricated based on immobiliza-tion of novel cyclometalated Rh(III) complex, [Rh(phpy-2N,C2)2(phen-dione)]PF6,where phpy-2N,C2is pyridine-2-yl-2-phenyl and phen-dione is 1,10- phenantroline-5,6-dione onto glassy carbon elec-trode (GCE) modified with multi-walled carbon nanotubes. The modified electrode shows stable andwell defined redox couple with surface confined characteristic at wide pH range and it showed excellentelectrocatalytic activity toward both oxidation and reduction of nitrite. Under optimized condition inamperometric measurement at applied potential 0.8 V, the detection limit and sensitivity were 23 nM,0.3 A/M at concentration range up to 300 M, while for applied potential −0.5 V, detection limit, sen-sitivity and concentration range were 80 nM, 0.6 A/M and 0.25–15 M, respectively. Furthermore,the proposed sensor shows excellent anti-interference ability towards various reducing and oxidizingcompounds such as uric acid, ascorbic acid, glucose, SO32−, I−, ICH2COO−, IO3−, B4O72−, Br−, SCN−,Cl−,BrO3−,Cr6+, Hg2+, Cr3+, As3+, Ag+, Ni2+Mn2+,Cd2+,Pb2+,Zn2+, Co2+and Fe3+at concentration ratio 100–1000.The practical application of the sensor as amperometric detector for flow injection analysis systems wasevaluated. Finally, the proposed sensor was successfully applied to the detection of nitrite in real sampleswith obtained satisfactory results.
