Wow, thanks. I'm going to try to answer most of the questions I've
received in one message as I'm overwhelmed by the quick multitude of
responses.
As I stated earlier, I haven't collected any room temperature data,
yet. So, I don't know the unfrozen mosaicity. It is very possible
that the crystals are simply mosaic at RT, too. I have tried
flash-cooling in liquid nitrogen and "gas cooling" in the cryo-stream,
I didn't notice a difference in the diffraction pattern.
My solvent content is on the high side about 67%. Additional crystal
details, I set the trays up at 20 degrees. The crystals take about 2
weeks to appear and another week to grow to full size. The crystals
are bipyrimidal and often 150x150x300 although sometimes smaller.
Typically, there's about 34-39% MPD in the well solutions. The well
solution freezes clear and I don't get any ice rings in my diffraction
patterns. I've tried looping the crystals directly out of the drop or
adding a few microletters of well solution and then looping, I didn't
notice a difference. I've been hesitant to start adding extras
fearing crystal cracking. I did however switch to freezing directly
in the automounter puck which was my one low mosacity crystal but I
had plenty of other crystals in the puck that weren't better then
before.
I was wondering if the MPD concentration could cause problems and
sounds like it might be. So, with the crystals I have I'll try higher
MPD to dehydrate and try freezing in lower MPD concentration or add
some other cryoprotectants to my current well solution. Although, I
might have to go find some propane.
If that doesn't work maybe, I'll try seeding at lower MPD
concentrations or pressure freezing.
Thanks again,
Mary
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