There can be no doubt that the phenidone-ascorbate pair is synergistic at pH 8.8 without sulfite. How does one differentiate between the synergism of electron transfer and that of superadditivity? What if I added sulfite to the PC-TEA working solution. Would I expect to find an increase in activity even if I kept pH constant? So far as I know, there is no ascorbic compound equivalent to hydroquinone monosulfonate. I am asking questions, not being derisive. I think one could make a PC-TEA-sulfite working solution, test it, and then make a PC-TEA solution with the same pH by adding a little TEA to the working solution without sulfite. Concentrations of P, C and the pH would be the same in both, the only difference being some amount of sulfite.