Improving the Interpretability of the Isotopic Data

At the Winter Conference on Plasma Spectrochemistry, which took place in Tucson, Arizona, from January 9^th–17^th, Martin Resano, a Coordinator of the Rapid Analysis Methods with Spectroscopic Techniques (MARTE) group and as part of the Aragon Institute for Engineering Research (I3A) at the University of Zaragoza (Spain), delivered a talk that highlighted his group’s current work.

Spectroscopy sat down with Resano at the conference to dive deeper into his research. Part I of our conversation with Resano touched upon his laboratory group and the work the MARTE group is conducting (1,2). Part II focused on the challenges and advancements in obtaining isotopic information using atomic spectroscopy (3).

In the final part of our conversation with Resano, he discusses how the use of partial least squares (PLS) regression improves the quality of the isotopic analysis data.

Spectroscopy: You applied both internal standardization and isotope dilution, along with PLS regression, to enhance analytical performance. Can you discuss how each of these strategies contributed to improving the quality and interpretability of the isotopic data?

Martin Resano: We have done bulk analysis of calcium and also isotopic analysis. The PLS regression is to improve the quality of the data of isotopic analysis only. So, whenever we do isotopic analysis, we have to use PLS when we do just calcium analysis. We use internal standardization to improve the quality of the calibration curves and to correct for some minor matrix effects. We use that for the termination of calcium in water because this is a line matrix. And with that, it's sufficient. This is one of the advantages I mentioned before because we were measuring calcium fluoride the molecule, but we're also measuring other elements, such as strontium, that we can use as the internal standard. That's for the internal standardization for the isotope dilution. We did it for milk because this is a heavier matrix. We have a strong matrix effect, so internal standardization is not enough to correct for them. That's why we have to use isotope dilution for calibration in order to get accurate results.

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

References

1. Wetzel, W. Inside the Laboratory: The MARTE Group at the University of Zaragoza. Spectroscopy. Available at: (accessed 2026-01-20).
2. IASA, Winter Conference on Plasma Spectrochemistry. IASA. Available at: https://iasa.world/winter-plasma-conference (accessed 2026-01-19).
3. Wetzel, W. Generating CaF Molecules for LIBS and LAMIS Analysis. Spectroscopy. Available at: (accessed 2026-01-23).