Question

A nanodrop cannot tell RNA for a DNA sample. How do you make sure RNA quality is acceptable? How do you determine the quality?

Answer 1

The quantity and quality of RNA can be determined by the UV absorption by means of a UV spectrophotometer.

The maximum absorption of RNA occurs at 260 nm, so its concentration can be determined by its optical density at 260 nm. A260 of 1.0 is equal to 40 µg/mL RNA.

The protein contamination (RNA purity) can be determined by calculating the A260/A280 ratio. The A260/A280 ratio of a pure RNA is, 2.1; and the purity is acceptable if the ratio ranges between1.8 to 2.0.