Re: Calibration of Pipettes

> Of course these along with the dirty pipettes may be cause. But in
> Chemed-L (another forum), two of people are of the view that this is
> tolerance not precision. ANother person there asserts my observations
> that his students never got close to the stated mean, they are always
> less volume. That is they assert my second view.

That they are always "less volume" sounds like the students may not be
using the correct technique for dealing with the curvature of water due
to surface tension. The bottom of the meniscus is the proper place to
measure (and I suppose the top of the meniscus for nonpolar liquids in
a glass pipette). I actually squat down to get a direct line of sight
on the liquid level while measuring.

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