One of the components of the mass spectrometry workgroup's mission is to provide other groups within NIEHS access to mass spectrometric analyses on a service basis. The workgroup provides the following services on an ongoing basis: 1) low and high resolution electron impact (EI) mass spectra; 2) low and high resolution chemicals ionization (CI) mass spectra; 3) negative ion chemical ionization (NICI) mass spectra; 4) gas chromatography/mass spectrometry (GS/MS) in conjunction with EI, CI, and NICI MS; 5) thermospray (TSP) liquid-chromatography/mass spectrometry (LC/MS) in conjunction with CI snf NICI MS; 6) electrospray ionization (ESI) MS coupled with capillary electrophoresis and nanoscale packed LC; 7) fast atom bombardment (FAB) under both positive and negative ion conditions; 8) continuous flow FAB/MS and FAB/MS/MS under both positive and negative ion conditions; and 9) tandem MS in combination with positive and negative ion FAB, ESI, EI and CI MS. We also provide high performance liquid chromatography (HPLC) and capillary zone electrophoresis (CZE) support. During the past year approximately 900 MS analyses have been performed on a service basis (not including collaborative work).