normal-phase chromatography on an nh2 column in methanol-ethyl acetate ( 3.97 ) at an elution rate of 2.0 ml/min allowed quantitation of thymine-containing ( thymine-thymine plus thymine-uracil ) pyrimidine dimers at levels as low as 0.1 % of the total radioactivity as thymine in dna .
C0041917
uracil
C0040087
thymine