Thiol-disulfide exchange between the AM and the AM-GSH conjugate in the presence of excess DTT and NAC. The AM and the AM-GSH conjugate were generated as described for Fig. 6. For thiol-disulfide exchange, DTT or NAC was added at 5 mM, as described under Materials and Methods. A, traces a, b, and c, EICs for the AM at m/z 356.1 for samples incubated with water, DTT, and NAC, respectively. B, traces a, b, and c, EICs for AM-GSH at m/z 661.0 for samples incubated with water, DTT, and NAC, respectively; trace d, same as trace c except recorded at m/z 517.1 for the AM-NAC conjugate.