Year: 2026
Type: preprint
Abstract: The spatial mapping of fluorine in solid samples is heavily hindered by its high ionisation potential in conventional positive-ion ICP-MS. To overcome this limitation without using complex plasma modifiers or mass shift strategies, we introduce laser ablation negative-ion ICP-MS (LA nICP-MS) as a direct approach for fluorine imaging. We systematically optimised the critical instrumental variables governing dry aerosol transport and negative ion extraction, revealing that the 19F signal is strongly driven by the conditions in the extraction interface rather than the core plasma thermodynamics. Operating at a lower RF power (down to 850 W) cools the extraction zone and promotes electron attachment, while a deflector voltage between 10-12 V provides optimal focusing of the negative ion beam under dry plasma conditions. Using matrix-matched gelatine standards, the method demonstrated excellent linearity and a representative limit of detection (LOD) of 10.2 µg g-1. The analytical performance of the method enabled mapping of the fluorine distribution in a cross-section of a honeybee (Apis mellifera) exposed to a perfluorohexanesulfonic acid (PFHxS) diet, revealing clear fluorine localisation within the abdominal gut architecture. Furthermore, simultaneous detection of 35Cl and 32S demonstrates the potential of LA nICP-MS for the multi-element imaging of non-metals in biological tissue. Overall, this study establishes LA nICP-MS as a direct alternative for fluorine imaging and provides basis for extending negative-ion ICP-MS to other challenging non-metals in complex solid samples.
Source: ChemRxiv
Institutions: University of Graz, Institute of Chemistry, James Hutton Institute
Language: English
Subfield: Analytical Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
Funder: Karl-Franzens-Universität Graz
OpenAlex ID: W7212183123