1. Make up a serial dilution of 0.2 ml DNA standard (0-100 mg/ml).

2. Dilute the sample to 0.2 ml with a concentration of 10-80 mg/ml.

3. Mix 0.2 ml of DNA standard or sample with 0.2 ml of 1% diphenylamine/0.5 M sulfuric acid/glcial acetic acid.

4. Boil for 10 minutes.

5. Cool on ice.

6. Read the absorbance at 595 nm.