Quantitation by gas chromatography-chemical ionization-mass spectrometry of phenylalanine mustard in plasma of patients.

An unambiguous and sensitive method based on gas chromatography-chemical ionization-mass spectrometry has been developed to quantitate L-phenylalanine mustard and has been applied to measure levels in plasma of five patients receiving 0.15 to 0.25 mg/kg (10 to 17 mg) of the drug p.o. Peak plasma levels of 50 to 190 ng/ml were found to occur between 0.7 and 2.3 hr after ingestion. The time for the plasma level to fall to one-half of the peak value varied from 0.6 to 3 hr, and very low levels (less than 2 ng/ml) were present by 24 hr.