[Archer]

Hi all,

Is it possible that the surface tension of water is preventing solvated molecules from coming into contact with a floating seed crystal?

This question comes from an unusual occurance today, while recrystallising an amine hydrochloride from water.

The first attempt crashed out rapidly due to dust and lint in the sample. This was reheated and passed through a syringe filter into a clean beaker.

When it returned to room temperature I deftly dropped a seed crystal of the correct morphology into the beaker.

However it just sat on the surface, despite being more dense than water.

After 3 hours the seed is just sat there, no crystals are forming and the seed is no larger than it was before.

I have never seen this happen before and I don't think I could repeat it again in 100 tries.

Has anyone else encountered this?

[discodermolide]

Never seen it myself as I always was crystallising 100kG or more.. But I am aware that this can happen, use a "heavier seed". Or a microliter of octanol should break the surface tension.

[Archer]

It's sitting on the naught spot (balance plinth) overnight. Perhaps the seed will achieve something by the morning.

Problem is I have only a very small amount of crystals and all of them are twinned, this was the only single crystal available.

I will know in 12 hours time