Assuming we had a sample of pure DNA, diluting it with known amounts
of a solvent would be trivial. The solvent could be water, or it could be a
preservative. The resulting calibration cuvette could be checked using a
lab spectroscope.
More interesting would be to add the DNA to acrylic resin to cast a long
plastic sheet 1 centimeter thick, and then cut it up into slices that are the
same shape as a cuvette. Again, testing it using a lab spectrometer would
provide the desired confidence that the embedding resin does not alter
the light at the two or three frequencies we are interested in for DNA
quantization.
The preserved DNA would be periodically checked to ensure that it has not
degraded over time, and the calibration samples could be checked against
one another for consistency to get statistics on accuracy. Given that most DNA
quantization readings I have seen seem to expect no better than 10% accuracy,
(i.e. readings of 1.8 or 2.0), the bar does not seem to be set to high for DIY.
Another approach would be to find stable molecules that could be added to plastic
that absorb light at the target wavelengths, and add them to the plastic in calibrated
amounts to simulate the effects of two concentrations of DNA.
-----
Get a free science project every week! "http://scitoys.com/newsletter.html"On Sat, Nov 26, 2011 at 10:11 AM, Cathal Garvey <cathalgarvey@gmail.com> wrote:
Actually, I have seen known concentrations sold; as ladders. If you add
up all the bands' concentrations you would have a known overall
concentration of DNA. The problem being that your ladder is suspended in
an unknown buffer; you could precipitate and resuspend, but you'd have
to be confident of your precipitation efficiency or you won't know how
much of the DNA you successfully recovered.
Any companies sell ladders in plain T.E., by any chance?
On 26/11/11 15:12, John Griessen wrote:
> On 11/23/2011 01:25 PM, Simon Quellen Field wrote:
>> The Beer-Lambert law will be linear between the two samples of known
>> concentration.
>> The sample will lie between those two known concentrations, and can be
>> linearly
>> interpolated easily. This can get you much higher accuracy than
>> looking up molar
>> absorptivities in a table and multiplying.
>
> Sounds like a good method -- three cuvettes or three nanodrop-like volumes.
>
> On 11/23/2011 01:33 PM, Nathan McCorkle wrote:
>> I've never seen a sample of known
>> concentration being sold
>
> What stops you from using a standard, but unknown in absolutes, references?
> You can make the low end of the range by diluting the high concentration
> reference.
> That would give you great relative accuracy, with low cost.
>
> JG
>
> PS nanodrop style may not be possible in OSHW for patent reasons.
>
--
You received this message because you are subscribed to the Google Groups "DIYbio" group.
To post to this group, send email to diybio@googlegroups.com.
To unsubscribe from this group, send email to diybio+unsubscribe@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/diybio?hl=en.
You received this message because you are subscribed to the Google Groups "DIYbio" group.
To post to this group, send email to diybio@googlegroups.com.
To unsubscribe from this group, send email to diybio+unsubscribe@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/diybio?hl=en.
0 comments:
Post a Comment