I didn't use any sulphite in my Q&D trial. I did, however, try the same amounts of p-aminophenol and ascorbic acid with KOH as alkali. Total disaster. Very dense fog. pH was much higher than with carbonate. I attribute that to the fact that although the same number of K molecules is used in each case to form the aminophenolate, a little extra carbonate does not have the same effect on pH as a little extra KOH. The ascorbic acid becomes the nearly neutral ascorbate in both cases. Thus, the pH is practically all due to the potassium aminophenolate when carbonate is used.
Originally Posted by Ian Grant
If ascorbic acid behaves with p-aminophenol as it is theorized to do with Metol, it will regenerate oxidized aminophenolate. By keeping the pH below the point where ascorbate is a developing agent, I should be able to increase the relative amount so as to extend the storage life of a stock solution greatly. If it is successful, it will probably be a great disappointment.