The low detection limit of Hoechst 33258 is ~ 5 ng/ml.

1. Make a Hoechst 33258 stock of 0.1 mg/ml.

2. Make up a serial dilution of 1 ml DNA standard (0-1000 ng/ml) with TE.

3. Dilute the sample to concentrations between 100-800 ng/ml in 1 ml TE.

4. Mix 1 ml sample or standard and 1 ml Hoechst 33258 (0.1 mg/ml). Mix.

5. Read with a fluorometer.