Figure 2

Quenching of HRP-generated light output by an antioxidant. A: Light generation of the HRP-catalysed luminol reaction was triggered by the addition of H₂O₂ (at time t₀ = -36 s). The reaction is quenched by the addition of an antioxidant when a constant output signal is established. Here Trolox™ ((±)-6-Hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid) a water soluble derivative of tocopherol (vitamin E) was used. The antioxidant is oxidised by H₂O₂ thus inhibiting the HRP-catalysed reaction. When the antioxidant is depleted, the HRP reaction resumes and the light signal recovers. B: The time point of signal recovery t_r depends on the amount of added antioxidant and is defined here as the time where the rate of signal increase is maximum. The curves here are derived from the curves in A and represent the first derivative of the running mean (n = 10) on the raw data. Luminescence is given here in counts per second (cps) and its recovery in cps per s.