Fig. 2. Selectivity of PNCLversus cations and reactive sulphur, oxygen, and nitrogen species. Chemiluminescent emission at 525 nm of 20 μM PNCL and 200 μM biologically relevant analytes in 20 mM HEPES (pH 7.4). Bars represent chemiluminescent emission at 525 nm at 4, 8, 12, 16, 20 min after addition of reactive species. Legend: (1) ONOO^–, (2) Cys, (3) DEA NONOate, (4) GSH (5 mM), (5) GSNO, (6) H₂O₂, (7) Angeli's salt, (8) KO₂, (9) Na₂S, (10) Na₂S₂O₃, (11) Na₂SO₄, (12) NaNO₂, (13) HO˙, (14) OCl^–, (15) ^tBuOOH, (16) ¹O₂, (17) Na⁺, (18) Mg²⁺, (19) K⁺, (10) Ca²⁺, (21) Zn²⁺, (21) Fe²⁺, (23) blank. Error bars are ± S.D. All experiments were performed in 20 mM HEPES or 20 mM PBS (pH 7.4), containing <1% DMSO.