Fig. 8. Ratio of emission intensities at 525 nm upon excitation at 480 and 510 nm in time after treatment with different concentrations of GSH (5, 3, 1 mM). Probe 4 (A); probe 5 (B); probe 6 (C) (5 μM probes 4–6; DMSO/HEPES buffer 2 : 1, 0.1 M, pH 7.4, 37 °C).