Similar to these ex situ simulated-crossover experiments, losses in 2,6-DHAQ were also observed after its addition to ferricyanide (Figure ). Interestingly, the measured 2,6-DHAQ loss rate, (3.33 ± 0.08) x 10 -5 mol dm -3 h -1 , was nearly two orders of magnitude slower than the loss rate of ferricyanide, suggesting that ferricyanide losses are occurring via a catalytic process involving 2,6-DHAQ. To further test this hypothesis, ex situ simulated-crossover experiments were repeated at different anolyte:catholyte mixing ratios, revealing that 2,6-DHAQ and ferricyanide losses were both maximised at a ~1:20 molar ratio (Figure ).