Mass spectrometry of thio analogues of pyrimidine bases: Correlation of the intensities of the M+˙ and the [M – ˙SH]+ ions of 2-alkylthiouracils

The mass spectral fragmentations of eight 2-alkylthiouracils with C₁₀, C₁₂, C₁₆ and C₁₈ in the alkylthio group were investigated. Fragmentation pathways are proposed on the basis of accurate mass and matastable transition measurements. The correlation between the intensities of the M⁺˙ and [M - ˙SH]⁺ ions of 36 2-alkylthiouracils is discussed. The data obtained create the basis for distinguishing structural isomers.