Hitachi U-5100 Instruction Manual page 127

Explanation 3-7 Set Wavelengths in DNA Measurement
On the absorption spectrum of an aqueous nucleic acid solution, absorption has the minimum
point near 230 nm and the maximum point near 260 nm. The wavelength of maximum absorption
varies with the base content and sequence in the nucleic acid. It is known that the ratio of
A260/A230 is approximately 1.8 with DNA and 2.0 with RNA.
Also, because the coexisting protein have a maximum absorption point at 280 nm, sample purity
can be estimated by taking the ratio of A260/A280. When the ratio is smaller than 1.8 in the case
of DNA, protein may be coexistent. Conversely, it is known that the ratio becomes larger under the
coexistence of RNA.
Abs
1.5
1.0
0.5
0.0
Excerpt from BUNSEKI KAGAKU BINRAN, 5th revised edition by The Japan Society of Analytical
Chemistry (page 400)
Setting Item
Delay (s)
200
Absorption spectrum of salmon testis DNA
Description
After the [START] key is pressed, the system waits
for the time period set here and then starts
measurement. This parameter is settable in a range
of 0 to 9999 sec in steps of 1 sec.
Set the parameter when you want to start
measurement after a specified time period, including
when measuring a sample after its temperature
reaches the room temperature. Enter "0" if the delay
time need not be set.
300
3 - 63
3.2.3
(cont'd)
nm
400