Protocol Online logo
Top : Forum Archives: : General Lab Techniques

pH and types of containers for solution storage - (Jul/17/2005 )

I was just curious if there was a set rule as to what types of containers should be used for storing solutions of acidic pH. In general, should acidic solutions be stored in glass containers as opposed to a polypropylene Falcon tube?




As far as I know there are no real rules, as different substances react differently with different containers, for instance HF (hydrofluoric acid) will react with glass, but not with plastics, whereas phenol will melt some plastics but won't affect glass. Check compatibility lists on the web or MSDS if concerned.



Thanks. Just making sure I wasn't completely glazing over something way back from gen chem.


Glass is good for most things, with the already mentioned exception of HF and for strong bases (5N NaOH, e.g.) which have a tendency to etch the glass. These should be stored in plastic. Dilute NaOH or KOH, however, is unstable, and absorbs CO2 from the air to form bicarbonates, so you should be careful of storing weak solutions for long periods of time.

Watch out for the caps on glass bottles when you are using them to store organic solvents. The caps are often the first things to go. Also, watch for disposible pipets used with chloroform or phenol/chloroform. They don't go well together. Use glass pipets. Pipet tips seem to be fine with chloroform, however.