Fig. 1.

TCBQ and H₂O₂ can produce two-step CL, even in the absence of fluorescent agents. (A) Two-step CL could be produced by TCBQ and H₂O₂. TCBQ, 0.1 mM; H₂O₂, 100 mM. (B–D) The effects of TCBQ, H₂O₂, and pH on CL production by TCBQ/H₂O₂. TCBQ, 0.2 mM; H₂O₂, 5 mM. (E and F) The second-step CL produced by TCBQ/H₂O₂ is the same as the CL by TrCBQ–OH/H₂O₂: Emission spectra (E) and time course (F). TCBQ, 0.1 mM; TrCBQ–OH, 0.1 mM; H₂O₂, 100 mM. All reactions were carried out in Chelex-pretreated phosphate buffer (0.1 M, pH 7.4).