The Moving Wire




Studies of biogeochemical processes are fundamentally limited by our analytical capabilities. Compounds and mixtures that are amenable to analysis fall within what is often called the "analytical window," and the analogy with a clear pane of glass – set into a much larger opaque wall – is appropriate. As we look through the window we see what is happening inside our window, but outside our field of view we can only guess at what is going on.

We are therefore working to develop new techniques for measuring stable isotopes in compounds that are too involatile to analyze by gas chromatography. These include such biologically important molecules as RNA and proteins, as well as much of the complex sedimentary organic matter present in most rocks. Our general approach is to use a "moving-wire interface" such as the one shown above that was originally developed by Finnigan-MAT. In essence, the liquid sample is dried onto a thin wire, which then carries the nonvolatile sample into the mass spectrometer. We are currently building a second-generation moving wire here at Caltech, and are looking for students or postdocs interested in applying this new instrumentation to biogeochemical research.