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Given the following coupled reactions: $$\ce{glucose + O2 + H2O + glucose~oxydase -> gluconic~acid + H2O2}$$ $$\ce{H2O2 + TMB(star) -> TMB}$$

Identify:

  1. A potential reagent or product that could act as a decoupling site leading to a falsely high glucose concentration.
  2. A potential reagent or product that could act as a decoupling site leading to a falsely low glucose concentration.

Note: The second reaction is just hydrogen peroxide reacting with $\ce{3,3',5,5'-Tetramethylbenzidine}$, to form the more absorbent version (I can't remember if it's reduced or oxidized).

The experiment involves running the above reaction on a sample with an unknown amount of glucose, then running the sample through a spectrometer to determine the absorbance and thus the concentration of glucose.

The only thing I can think of is that if the sample warmed up too much you might lose some of the oxygen, resulting in a lower than expected glucose measurement. Though you'd have to lose enough oxygen for it to become the limiting reactant, which I don't see as being too plausible.

I can't find anything anywhere else and I'm stumped.

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