One of the biggest challenges of modern real-time analytical techniques is dealing with matrix effects, and in particular the enormous potential concentration range of these matrix species in a sample whose characteristics are not well known.
Real-time analytical techniques by their nature do not utilse a chromatographic separation step, so the sample interrogation is performed on the analytes and matrix as a whole. The analytical chemist is faced with the problem of determining accurate concentrations of compounds at trace levels, in the presence of a complex mixture of speices at potentially vastly higher concentrations.
Selected Ion Flow Tube Mass Spectrometry (SIFT-MS) is a real-time mass spectrometry technique that is powerfully suited to deal with this problem. The uniquely soft chemical ionsiation that is employed provides extreme sensitivity, consistently across virtually all VOCs, delivering a dynamic range that spans over 6 orders of magnitude.
Consider the example pictured here in which real-time continuous live-stock odour emmisions are being monitored. In this case the key species of interest include low-odour-threshold reduced sulfur compounds but the matrix also contains amines at concentrations up to one million times higher.
This is an analytical problem that would confound conventional techniques. But the broad dynamic range of SIFT-MS renders this real-time continuous monitoring application entirely routine.