Does citric acid "decay"? Hi I'm preparing about 80 mL of citric acid from anhydrous crystals, using 1g of crystals to 1 mL of de-ionized water. It is for the purposes of etching GaAs with a 3:1 citric acid to H2O2 (by volume) mixture. I wait at least a day after making the acid from the crystals before use. My question is, does citric acid "decay" (become weaker) over time? I might be imagining things, but it seems that when I use acid that has been sitting around for more than 4 days, my etching rate is slower and/or inconsistent. The acid is stored in a clear glass container in an acids cabinet. Thanks!