High-pressure electron capture mass spectrometry

High-Pressure Electron Capture Mass Spectrometry (HPECMS) has demonstrated extraordinarily high chemical specificity and sensitivity in the analysis of numerous compounds of environmental and biomedical interest. In the application of this technique, however, difficulties in the form of unexpected EC mass spectra and unexplainable variations of sensitivity are often noted. In this review article, two distinct sets of processes that determine the nature of the ions produced in an HPEC ion source are reviewed and discussed. The first set of gas-phase processes comprises the electron capture mechanism, leading to simple fragment and molecular anions. The second set of processes is imposed by physical realities of the typical HFEC ion source. These secondary processes can have large effects on the sensitivity of HPECMS to various types of EC-active compounds and can lead to the production of unexpected lolls in HPEC mass spectra. It will be shown that the successful use of HPECMS is greatly facilitated by an understanding of all of the above interactive factors. The scope of this review is limited to the processes that will be important only under the relatively pristine ion source conditions that are typically established for the trace analysis of EC-active compounds introduced in very small quantities by capillary-column gas chromatography. (C) 1996 John Wiley & Sons, Inc.