Images of H2O2 acquired using an iPhone 6, a home-built dark box, and either (a) the time-lapse imaging application OSnap!, (b) the stock iPhone 6 camera application with exposure settings at maximum using 25 µL aliquots and aliquots of 0, 25, 50, 100, 150, and 200 µM H2O2 and 3.9 mM BPEA, 3.7 mM imidazole, and 2.2 mM CCPO in 9:1 EtOAc:CH3CN, or (c) the stock iPhone 6 camera application with exposure settings at maximum using 75 µL aliquots of 0, 25, 50, 100, 150, and 200 µM H2O2 and 3.4 mM BPEA, 3.2 mM imidazole, and 1.9 mM CCPO 9:1 EtOAc:CH3CN. Images were acquired 2–3 sec after addition of H2O2 as the final reagent.