Figure 4

Effect of pH on the fluorescence intensity of 1 μM H ₂ O ₂ reacting with 10 μM APF in the presence of 0.2 μM HRP and addition of either hydrochloric acid or sodium hydroxide for 24 hours. Inset shows the fluorescence intensity from pH 4 to 9. The fluorescence intensities roughly correspond to nM of H₂O₂ that would react with HRP, so that a fluorescence of 1000 equates to 1000 nM H₂O₂.