Materials:

• DNA you wish to quantify
• Beckman Coulter DU730 spectrophotometer
• Millipore Q water
• Quartz cuvette
• Kimwipes
• pen & paper
• pipetes, tips, tubes, etc

Protocol:

1. turn on the spectrophotometer
2. choose “dsDNA” and then “blank” from the touchscreen display
3. wait for UV light to warm up
4. while light is warming up, prepare a 1:20 dilution (5µl DNA + 95µl MilliQ water) in an Eppendorf tube
5. gather up quartz cuvette (quartz cuvette will be located either in the drawer marked “stirbars markers razors tape” in the lab or in the top right drawer of the desk in room 14047), P200, and tips and return to the spectrophotometer
6. on touchscreen display, change dilution to “20”
7. re-blank using quartz cuvette filled with H₂O
8. fill cuvette with DNA dilution and put into spectrophotometer
9. choose “read” on touchscreen
10. write down “conc” (in µg/ml), “abs“, & 260/280 ratio

    260/280 ratio should be close to 1.80

11. turn off spectrophotometer

See also:

• Beer’s Law
• Spectrophotometric quantification of DNA and RNA