DNA was quantitated on a Unicam UV4-100 UV/Visible light spectrophotometer
1. Add 10 mL of stock DNA to 990 mL TE. This is a dilution factor (DF) of 1/100
2. Use 1 mL quartz cuvettes
3. Blank the spectrophotometer with 1 mL TE
4. Take readings at 260 nm and 280 nm
5. Calculate the 260nm/280nm ratio. This ratio should be 1.8. If it is less than 1.8, there may be protein contamination. If it is greater than 1.8, there may be RNA present.
6. One optical density unit at 260 nm in a 1 cm path length is approximately equal to 50 mg/mL of double stranded DNA. Therefore the concentration of DNA could be calculated using the formula:
[DNA](mg/mL) = OD260 x 100 (1/DF) x 50