Analysis of pyrimidine bases in biological materials by gas chromatography-mass spectrometry.

Simultaneous detection by a combination of gas chromatography-mass fragmentography and gas chromatography-mass spectrometry for total ion monitoring was developed for determination of uracil, thymine and cytosine present in biological materials as pyrimidine bases, as their silylated derivatives. The detection limits for uracil, thymine and cytosine in the first method were 0.001 microgram/ml for plasma and 0.001-0.005 microgram/g wet weight for tissues. Those for uracil and thymine in plasma and tissues and for cytosine in plasma in the second method were 0.2 microgram/ml or g wet weight, and that for cytosine in tissues was 2.5 microgram/g wet weight. An accurate and sensitive assay for determination of pyrimidine bases was established.