Figure 4. Stern-Volmer plots showing (A) halothane quenching of free L-tryptophan in methanol, (B) halothane quenching of tryptophan in 1:1 (volume in volume) methanol:glycerol, and (C) lack of quenching of tryptophan fluorescence by diethyl ether. Excitation was at 295 nm, and the emission maxima were recorded at 330 nm. The tryptophan concentration was 10 micro Meter. Data are the means plus/minus SD of four experiments.