Re: [DIYbio] Re: Cheap capillary electrophoresis

Hi Gordana,
what I had in mind for optical detection was a simple USB microscope focused onto the capillary. You could then take a video of it (amcap), and then pick the video up with ImageJ and plot color vs time/frame number.

My ImageJ skills are weak - I knew it as NIHImage, and I never had my own Mac to run it on, so I have not yet figured how to do this. I know from the examples that it is possible to step through the video (avi) file and treat the images sequentially. I am short of time, so only playing with this a little.

Possible cheap detectors for this:

1) a uv source shining through the capillary onto yellow highlighter drawn on paper behind - monitor diminishing of the fluorescence when an aromatic floats past.

2) some variation of sybase green/ DNA ladder

I am quite impressed with the magnification/focusing possibilities of those usb cameras. It is not near spectrophotometer level, but it is very cheap, and looks quite robust. When I get it all going, I'll look at linearity.

My current update is that capillaries with silicone oil run well with pillbox red and 50mM NaHCO3 as running buffer (pH 7.8, supposedly, but not measured).

In answer to your other question, both ends of the capillary were in fluid.


On Wednesday, May 3, 2017 at 10:00:38 PM UTC+8, John Griessen wrote:
On 05/03/2017 08:52 AM, Gordana Ostojic wrote:
> Here is one


Hello Gordana,
You said about harristotle1's video:

 > I can't see from the video the other end of the tube and if that is in liquid. Anyway I did use similar thing (it's somewhere on
 > this board). It turned out that optical detection is hard (material issues with UV, lamps are expensive, power is demanding...) so
 > I found out most people work with dielectric detection.

Are you sure optical detection is still "hard" today?  How did you do the dielectric detection?  Measure capacitance of the
capillary circuit?

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