if your crystals are from 2 M AmSO4 without buffer, try to measure the pH in the drop, if possible. Or if you have plenty of crystals, transfer to 2 M AmSO4 buffered at a wide range of different pHs to see where the crystals are stable, before adding cryoprotectant. In the end, you may need to grow new crystals in the presence of buffer and, if possible, glycerol. The latter could allow direct freezing. Mark
On 5 Feb 2012, at 23:49, Theresa H. Hsu wrote: > Hi all > > Is there a list of conditions to be tried *first* for cryoprotectant? My > crystals diffract at room temperature capillary but no in 30% PEG 400. > Crystals are from 2 M ammonium sulfate. > > Thank you. > > Theresa
