Cleaning Quartzware Used to Digest Organics
John wanted to know the best way to clean quartz flasks that have been used to digest organic compounds. Currently, his glassware is typically soaked for about 24 hours in 25% v/v nitric acid in a plastic container, then rinsed in distilled water.
When our quartz has been exposed to organic compounds, including silicone oils/grease, we clean it by immersing it in a freshly prepared solution of 1:1 sulfuric and 30% hydrogen peroxide. The solution is of course very HOT and exposure to the skin will cause severe burns, so extreme caution is necessary. I typically prepare and use this solution myself or have a very experienced analyst use it. I will allow the solution containing the quartz to sit overnight in a hood.
Another way to rid the quartz of organics that are not organometallic in nature is to heat it in a muffle furnace at 550 °C overnight.
Nitric acid will attack organics when concentrated and heated under pressure, but it will not convert them to CO2 and water.
Please let me know if you have any questions, concerns, or comments.
Serving you in chemistry,
Paul R. Gaines, Ph.D.
CEO of Inorganic Ventures & Fellow Chemist
DISCLAIMER: Advice offered by the chemists at Inorganic Ventures is intended for the individual posing the question. Feel free to contact us to verify whether these suggestions apply to your unique circumstances.