[pantone159]

I want to make some metol and/or hydroquinone solutions, to explore any complexes these make, e.g. with transition metals.  The question is how to make them keep well (as much as possible).

What is the best pH to make these at?  Photo developers use alkali, but would these keep better in acid?

Photo developers add sulfite to protect against oxidation.  Metabisulfite would be more acidic, so maybe a good replacement for sulfite?

[woelen]

The only way to keep metol and hydroquinone reasonably well in solution is in combination with concentrated sulfite. The sulfite ion forms a compound, which is fairly resistant against aerial oxidation.

If you want to experiment with metal complexes, then of course you don't want the sulfite. So, I would suggest not to make solutions of metol and hydroquinone. Store them as solids and only dissolve them when performing experiments. Storing unstabilized metol- and hydroquiine solutions only results in spoiling your chems.