Concentration of DNA
drm21 at mole.bio.cam.ac.uk
Mon Nov 18 12:13:51 EST 1996
In article <Pine.PMDF.3.91.961118093456.551568441A-100000 at sask.usask.ca>,
fang at SASK.USASK.CA wrote:
>How do you measure DNA concentration accurately? By gel (agarose or
>acrylamide) or by spectrophotometer? What is the lowest concnetration you
>can get? Say the DNA is 500 - 1 kb in size. How do you measure very low
>concentration, eg. around 5 ng/ul, and you could not afford 1 ml of DNA
>sample for measureing?
>Thank you very much in advance.
Get a 50ul quartz cuvette for your spectrophotometer. (You usually need an
adaptor to raise it up high enough for the beam). I never understood why
people buy enormous 1ml (or worse still 3ml) quartz cuvettes when these
tiny ones are available.
Now, lets see, OD260 of 1.0 is about 50ug/ml or 50ng/ul so you won't be
able to dilute your sample much - but might you be able to splurge a whole
Alternatively IIRC, there is a way of measuring DNA conc's by photographing
spots containing DNA and ethidium bromide - I think
Maniatis^H^H^H^H^H^HSambrook et al describe it, though it never worked very
well for me. You need to do a set of standards in parallel every time....
Wellcome/CRC Institute, Time flies like an arrow...
Tennis Court Road,
Cambridge CB2 1QR Fruit flies like a banana.
Tel: [+44] (0)1223 334129 Email:drm21 at mole.bio.cam.ac.uk
Fax: [+44] (0)1223 334089
More information about the Methods