Detecting Iron Oxidation States in Liquids with the VOXES Bragg Spectrometer

TL;DR

This paper demonstrates a novel application of the VOXES Bragg spectrometer to identify and quantify iron oxidation states in liquids, with potential implications for food quality assessment.

Contribution

It introduces the MITIQO project, utilizing high-resolution X-ray emission spectroscopy with mosaic crystal Bragg spectrometry to analyze metal oxidation states in liquids.

Findings

Successfully detected oxidized iron in liquids

Spectral features correlated with oxidation states

Validated method with powdered iron samples

Abstract

Determining the oxidation states of metals assumes great importance in various applications because a variation in the oxidation number can drastically influence the material properties. As an example, this becomes evident in edible liquids like wine and oil, where a change in the oxidation states of the contained metals can significantly modify both the overall quality and taste. To this end, here we present the MITIQO project, which aims to identify oxidation states of metals in edible liquids utilizing X-ray emission with Bragg spectroscopy. This is achieved using the VOXES crystal spectrometer, developed at INFN National Laboratories of Frascati (LNF), employing mosaic crystal (HAPG) in the Von Hamos configuration. This combination allow us to work with effective source sizes of up to a few millimeters and improves the typical low efficiency of Bragg spectroscopy, a crucial aspect when studying liquids with low metal concentration. Here we showcase the concept behind MITIQO, for a liquid solution containing oxidized iron. We performed several high-resolution emission spectra measurements, for the liquid and for different powdered samples containing oxidized and pure iron. By looking at the spectral features of the iron's K$\beta$ emission lineshape, we were able to obtain, for a liquid, a result consistent with the oxidized iron powders and successfully quantifying the effect of oxidation.