calibrating gilsons

U58563 at U58563 at
Sun Sep 25 00:15:08 EST 1994

This isn't too sophisticated.  The main problem is turning the calibration
control, which is the INNER ring as seen from the top of the instrument.  Some
commercial person tried to convince me that you needed this special $600 steel
gizmo (a rod with two prongs, in other words) from Gilson to do it (he was NOT
from Gilson, and no insult intended to them), so I improvised with two
dissection probes melted through an eppendorf with a hole in the bottom, which
worked fine.  Or try those allen wrenches -- whatever works.  It's OK to just
pull the little thumb pad right off (with the little 200 ul label) and then
you can turn the cylinder.
   For all these calibrations (including the commercial people) it is simply
assumed that water has exactly 1 g/ml density, which given the amount of
variation in the pipettemen is about right -- you won't get it better than a
few parts in one thousand, so the temperature correction isn't important.  Just
use your analytic balance and your gizmo, and away you go.
   Cleaning out your pipettemen from the inside is something you can try out
for yourself also; it doesn't take any special care except NOT to lose the
little rubber ring and white plastic disk (try a P1000 first, with p20's they
are tiny!) I like to do it before starting pA+ RNA isolations, for instance,
to be sure no RNase gets in that way.  The ring and disk are subject to wear
and can/should be reordered/replaced eventually (like, when you start noticing
that glycerol doesn't come in -- it means there's an air leak!)

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