“…For sulfite ions, the linear regression equation is I (nA) = 2.1(±0.2) c (nM) (R = 0.9995) in the range from 5 μM to 1.0 mM, and the detection limit was 1.66 μM. Therefore, GNP-NH 2 exhibits better performance not only for the detection of nitrite ions (e.g., a detection limit of 33 nM, higher than 15 nM on Fe 2 O 3 nanoparticles decorated reduced graphene oxide nanosheets, 38 but lower than 46 nM on graphene oxide supported gold nanoclusters, 39 37 nM graphene oxide-silver nanocomposite, 40 200 nM on gold nanoparticles-sulfonated graphene, 41 250 nM on gold nanoparticle/graphene/chitosan, 42 and 0.2 mM on polyaniline/graphene/ferrocenecarboxylic acid composite 43 ) but also for the detection of sulfite. 42,44 The reproducibility of measuring 5.0 nM lead ions with GNP-Cl as well as 1.5 μM nitrite ions and 25 μM sulfite ions with GNP-NH 2 was checked via monitoring once with five freshly prepared electrodes or measuring five times with one electrode.…”