Submitted to: American Chemical Society National Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 8/24/2000
Publication Date: N/A
Technical Abstract: The issue of confirmation of identity continues to be a central challenge in residue analysis. This is especially critical for water quality studies in which the expected concentrations in sample extracts are in the 5 to 50 part per trillion range. HPLC/ion-trap/mass spectrometry/mass spectrometry [LC/IT/MS/MS] is an excellent tool for meeting this requirement. It provides a very high degree of analytical specificity at moderate cost primarily due to its sequential scanning capabilities in real-time from three modes of acquisition. First, while full-scan mass analysis on unknown chromatographic peaks may not yield a single structure, it always provides molecular weight information. Second, targeted zoom scans over narrower mass ranges encompassing higher resolution permits identification based on small differences in isotopic abundances. Third, sequential isolation of preselected precursor ions followed by collision induced dessication generates confirmatory product ions. Examples illustrating these approaches are shown for sulfonylurea, chloroacetamide, and imidazolinone families of herbicides.