I made a solution of 2.5 M glycine in water and filtered through 0.22 um stored at 4 C. After 2 months in storage, I noticed large clear crystals in my solution. Is this normal? How do I prevent this from happening? Thanks.
It’s normal for some things to crystallize out of aqueous solution, especially at reduced temperatures. Apparently glycine is such a molecule. Storage at room temperature might prevent the crystallization, but you might also get microbial growth if there are any critters in there. Try gently warming the bottle and see if the crystals go back into solution. Leaving it on the countertop overnight might be enough. If not, a 37C water bath might work. Autoclaving is very likely to do the job — be sure to use the liquid cycle. Solvent collisions can shake the molecules off the crystals, the question is how energetic the collisions should be.