Fig. (7) Plate reader assay with reductide is more dependent on dose of redox modifier pretreatment than plate reader assay with monochlorobimane.Reductide (A) is compared with monochlorobimane (B), which is non-fluorescent unless conjugated to low molecular weight thiols, in IMR90 fibroblasts following pretreatment with NAC or H₂O₂. Cells were seeded into a 96-well plate at a density of 50,000 cells per well and allowed to attach overnight. The following day, cells were incubated with vehicle, NAC, or H₂O₂ at the indicated concentrations for 60 minutes followed by washing and replacement of media with assay buffer containing monochlorobimane or reductide. Reductide or monochlorobimane signal was ascertained at the indicated time points of incubation.