off-topic: Phoenix robot problems - short summary of replies

From: Gregor Witte
Date: 20 December 2011 15:05


Dear CCP4ers,

Thanks a lot for all your replies. Additionally, I have to thank Art
Robbins, Dave Wright and colleagues from Art Robbins Instruments for almost
immediate replies and for taking care of our problems.
Besides of the normal wash steps that we do and of course a well prepared
protein sample (centrifuged at high speed, take supernatant), CCP4 users
have suggested the following:

- Lots of Phoenix users do a 0.1M NaOH wash after each cycle (e.g. using
reservoir 2 bottle), which seems quite reasonable and we have also
introduced it on our system now.
- More extensive wash steps in between the different users (longer NaOH or
Zymit wash). Other users increased the frequency of Zymit wash-steps (1
zymit wash every 10-15plates). We are now using an end-of-day-wash protocol
including Zymit and eventually do a Zymit wash every couple of users.
- Prevent dust everywhere if possible (we use HPLC grade water for the
system liquids in Reservoir 1 and 2, cleaned the bench etc.)
- ARI suggested pre-wetting of the nozzles with sample buffer prior to
aspirating the protein solution. This might prevent that "difficult
proteins" feel even more unhappy if they touch dry surfaces or wet surface
without any ions (like present after washing with water). I am going to try
this.
- As some of our proteins may indeed be difficult, ARI suggested a short 2M
urea aspirate/dispense step after dispensing the protein, prior to the NaOH
wash step.

We have changed all nozzles to new ones and introduced the steps described
above and at the moment it seems that we are running fine.

Thanks again for all your help and merry Christmas to all of you out there!

Gregor


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Dr. Gregor Witte