Microtrap interface for on-line mass spectrometric monitoring of air emissions

One of the problems in on-line mass spectrometric monitoring of air emissio ns is that whereas organic pollutants are present at trace concentrations ( ppm to ppt levels), background gases such as H2O and CO2 may be present at per cent levels. Moisture in particular is a source of serious interference . A sampling interface that eliminates these interferences but allows the c ontinuous introduction of organics into the mass spectrometer is presented. The interface consists of a micro-sorbent trap (referred to as the microtr ap) that selectively traps the organics, and then injects them into the mas s spectrometer via rapid thermal desorption with an electric pulse of simil ar to 1 s duration. Continuous (or near-continuous) monitoring is achieved by making a series of desorptions while the air Bows continuously through t he system. The applicability of this approach is demonstrated by monitoring the emissions from a catalytic incinerator. Copyright (C) 1999 John Wiley & Sons, Ltd.