In the present study, trimethylindium. trimethylaluminum and bis(cyclopentadienyl)magnesium are analyzed by using novel GC-MS technique. A stream of high purity helium is purged through the material via a stainless steel bubbler of the type used to deliver the precursor for use in MOVPE film growth. The stream containing helium and volatile fractions from the source compound Lire swept into a sample loop. injected onto a chromatographic capillary column. and the eluted fractions subsequently indentured and sometimes quantified by mass spectrometry, A profile of headspace fractions is presented. along with their respective mass spectra. The relationship between the concentration of impurities in trimethylindium and the electron mobility in grown InP layers is explored. (C) 2002 Elsevier Science B.V. All rights reserved.