[3dem] Vitrobot mark III vs mark IV

Bob Grassucci rg2502 at columbia.edu
Fri Apr 8 09:36:18 PDT 2011

Hi Martin,
Unfortunately it depends on how the zero force was set on the Mark IV 
and there is no standard way they are calibrated.  While the mark 3 
changed the position of the grid relative to the V of the blot pads the 
Mark 4 changes the distance the pads are away from each other.  In other 
words if the the zero force on one mark 4 is set closer than another 
it's blot force for a particular setting will be stronger than for 
another where zero was a bit further apart.  Initially the Mark 4's zero 
force was not set at all which lead to irreproachable results.

I can not recall now is 3 mm deeper into the v than -3mm ?  If so I 
would start with a positive blot force and once you get the right force 
do not change it with similar grids and sample (this can also change 
with sample and grid type).  I hope this helps.  Good luck.

On 4/8/2011 11:53 AM, MP Cheung wrote:
> Hi All,
> Does anyone know how the 'Blotforce' setting on the Mark IV compares to
> the 'Offset' setting on the Mark III? If I have previously used a 3mm
> offset in the Mark III, what blotforce would I need to set in the Mark IV
> to replicate the same conditions?
> Thanks,
> Martin
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