[The determination of free and bound methylated nucleobases in food]

The following method was developed for the qualitative and quantitative determination of methylated purine and pyrimidine bases in food; some RNA-rich food was also investigated. The bases were liberated from nucleic acids, nucleotides, and nucleosides by acid hydrolysis with trifluoroacetic and formic acid (1/1, V/V) at 240 degrees C in a pressure-digestion system. Purification and fractionation of hydrolysates were achieved by sorbent extraction with an RP 18 column and a cation exchange column. The major and methylated nucleobases were determined by ion-exchange chromatography and reversed-phase-HPLC.