Trace analysis by gas chromatography/mass spectrometry (GC/MS) using a tandem double-focusing/quadrupole instrument

Analysis for oestradiol bis-tert-butyldimethylsilyl ether by gas chromatography/mass spectrometry (GC/MS) with selected reaction monitoring ([M]+.----[M-C4H9]+) using a tandem double-focusing/quadrupole instrument gave a detection limit below 10 pg. During analyses of a plasma extract, the selectivity of detection was superior to conventional selected ion monitoring. A parent ion resolution of 5000 was used to eliminate detection of all components but the chosen analyte.