How Will Speciation Analysis Evolve?

Hyphenated techniques in spectroscopy combine two or more analytical methods. These usually are a separation technique, such as gas chromatography (GC), liquid chromatography (LC), or capillary electrophoresis (CE), with a spectroscopic or spectrometric detector like mass spectrometry (MS), infrared (IR), or atomic spectroscopy, and the integration of these methods deliver enhanced chemical insight. By coupling separation and detection into a single workflow, these techniques allow complex mixtures to be resolved and individual components to be identified and quantified with greater selectivity and sensitivity than either method alone.

These approaches are becoming more common as mixtures and samples are becoming more complex. We asked Alexander Scheeline, a distinguished analytical chemist and Professor Emeritus in the Department of Chemistry, School of Chemical Sciences at the University of Illinois at Urbana-Champaign, about this trend and how it relates to speciation analysis.

Spectroscopy: With the rapid expansion of hyphenated approaches, how do you envision the role of speciation analysis evolving?

Alex Scheeline: Speciation is typically thought of as coming from the chemical details of a sample and for SIBS and for LIBS. Since we're looking at bulk metals, there really isn't a bunch of chemistry other than metallic solutions or metallic aggregates. If we have enough spatial resolution, we're looking at an iron carbide versus an iron manganese region in a sample. If a spark is looking at a large region, then speciation is what's causing noise in the signal because the sample is inherently heterogeneous. I don't think that speciation in solids is actually the right question. It's spatial heterogeneity and thermal properties of the sample that lead to noise or interference in the overall measurement, rather than having some chemical clustering changing the spectral properties once the metal is volatilized.

One of the points that I made in my presentation is that if you're attacking a given position on a metal with either repeated laser firings or repeated sparking, that the sample that you get on the second firing is the sample that you had on the first firing changed by the effect of the first laser pulse of the first spark, so you have an iterated process. We started doing work on iterated processes back in the 1980s and then got diverted onto many other issues. I think that's something that might well be addressed by some newer and younger individual.

This video clip is the final part of our conversation with Scheeline. To stay up to date on our coverage of the Winter Conference, click here.