“…Koren et al [69] use a highly photostable luminescent crystal coupled to the PB/PW pair, using the inner-filter effect to correlate changes in luminescence to changes in H2O2 concentration ( Figure 6). However, Koncki et al [70] observed not only an optical response of PW to H 2 O 2 , but also to chromate, dichromate, permanganate, chlorine, bromine, iodine, hexacyanoferrate(III), Fe(III), as well as a slow response to O 2 resulting in a drifting baseline. Cross-sensitivities to K + , Na + , and pH were observed in PB films, and PB can be reduced to PW by H 2 S, ascorbic acid, and various mercapto-compounds [70].…”