[Automated-sequencing] Weird chromat, part 2
Phillip San Miguel
pmiguel at purdue.edu
Thu Jun 23 15:09:10 EST 2005
Nice! It never occured to me to think of viscosity.
I tend to think about electrophoresis as only involving charged
products migrating through a matrix because of an applied electrical
field. But DNA is charged and can be viscous. Those capillaries have a
narrow diameter. So drag caused by viscosity could play a role.
Maybe the skewing I see is from surface interactions at the interface
between the capillary inner surface and the polymer.
Jean Renaud wrote:
> The solution to obtain good chromatogram is to increase dilution with
> formamide in order to decrease viscosity of sample.
> Hi Phillip,
> Sometimes, presence of genomic DNA in the prep may give some viscosity
> to it and cause trailing of peaks. Effect is more important as molecular
> weight of fragments increase.
>> Take a look at this screen capture:
>> (It is only a 74 kbyte .png file.)
>> Anyone have an idea of what is going on? Note that the peaks look
>> pretty good around 200 bases, but by 500 bases something is clearly
>> wrong. The right-side edge of the peaks come up pretty high above
>> baseline. But the left-side edge looks much better. I guess the peaks
>> are "skewed".
>> Has anyone seen this before?
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