need: info on A260-A280 absorbance measurements

Hiranya Roychowdhury hroychow at NMSU.EDU
Thu Oct 17 09:14:14 EST 1996


At 04:08 PM 10/16/96 +0200, Manuel G. Claros wrote:
>On 14 Oct 1996, Guido Hooiveld wrote:
>
> > I was told an A280/A260 ratio
>
>Note: A260/280
>
> > theoretically limit is 2.0. However, I often find a ratio larger than
2.0; like 2.1 to 2.2. So, 
> > is this (theoretically) value of 2.0 correct, if yes, does anybody have
a suggestion why I find 
> > values >2; if not, what is this value? 
>
>You have degradated nucleotides.



No, ...degraded nucleic acids.


>
> > multiply A260 with 50 to obtain the concentration (ug/ml), or use 35?
Which value is correct?
>
>50 for oligonucleotides and 35 for dsDNA


No!! ...It is the other way around. 



>
> > Any comments would be appreciated!
>
>I hope this helps
>
>Manuel G. CLAROS, Ph.D.
>Bioq. & Biologia Molecular
>Fac. Ciencias
>Campus de Teatinos
>E-29071 Malaga
>
>
>



Dr. Hiranya Sankar Roychowdhury
Plant Genetic Engineering Lab.
New Mexico State University
Las Cruces, NM 88003
Ph. (505) 646-5785
hroychow at nmsu.edu




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