Isolation of drugs and drug metabolites from biological fluids by use of salt-solvent pairs.

Abstract

Simple rapid procedures based on salt-solvent pairs have been developed for the isolation of drugs and drug metabolites from urine, plasma, and breast milk. The best overall recovery of drugs (84-104%) was obtained by using ammonium carbonate—ethyl acetate extraction. Internal standards were added to the biological samples before the isolation procedure was begun; standards labeled with stable isotopes were preferred. The isolated drugs were quantitated by selective ion detection, with use of an LKB 9000-PDP 12 in electron impact mode, a Finnigan 1015-PDP 8/1 in chemical ionization mode, and an atmospheric pressure ionization mass spectrometer. Sensitivity of detection was in the nanogram to picogram range.