I need to wash glass ampoules to remove organic residues and other chemical contaminant. Which kind of acid and which concentration of it is needed?
Dear friend Sima Zarei
To clean glass equipment like ampoules, use a diluted hydrochloric acid solution (5-10%) for effective removal of organic residues and chemical contaminants. Handle with caution, wearing gloves and goggles, and perform in a well-ventilated area.
Hydrochloric acid cannot dissolve all organic adhesions because it is a reducing acid. Strong oxidizing acids and acid mixtures, which decompose practically all organic residues, are more effective. For example, these are the following:
If you are dealing with stubborn organo-metaliic residues, or residues of unknown nature, dip it into conc. sulfuric acid (98%) , warm to near 150 C, and slowly add Conc nitric acid (>30%). A quite dense white fume (not brown) is likely to emerge unless metal is in too high amount. Keep adding little by till till charred carbon residues are cleared off, and keep the solution fuming (not necessarily boiling), you may add concentrated hydrochloric acid (no more than 25% volume of sulfuric acid) if you have metals or ores stuck that are easily passivated, but add these very carefully. When you do not have hydrogen peroxide at your hand, any organo-metallic waste that is not acidic-ceramic (like silica) rich is likely to be dissoved by 30 minutes, or 1 hour max. I have used this technique to clean some most-stubborn level of MnO2-Al-biopolymer composite residues from glass petri dish.
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