Sub-micrometer scale synchrotron x-ray fluorescence measurements of trace elements in teeth compared with laser ablation inductively coupled plasma mass spectrometry.

Background: Elemental analysis of teeth allows for exposure assessment during critical windows of development and is increasingly used to link early life exposures and health. The measurement of inorganic elements in teeth is challenging; laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is the most widely used technique.

Objective: Both synchrotron x-ray fluorescence (SXRF) and LA-ICP-MS have the capability to measure elemental distributions in teeth with each having distinct advantages and disadvantages.

Methods: In our study, we compared these two methods for teeth elemental quantification. SXRF was able to achieve spatial resolutions of 0.3 µm and is non-destructive while giving similar elemental quantification results to LA-ICP-MS.

Results: For particular elements, SXRF can offer lower detection limits but depends on the specific beam intensity. The comparison between methods revealed less than 10% disagreement between quantification results from LA-ICP-MS and SXRF.

Impact: Synchrotron x-ray fluorescence can be used to effectively quantify elemental distributions in teeth at a nanoscale resolution and is comparable to current laser ablation inductively coupled plasma mass spectrometry. Both methods offer advantages and disadvantages with LA-ICP-MS offering in-lab analyses, whereas SXRF offers much finer spatial and temporal scales and better detection capabilities. For studies focused on fine scale changes in structure, SXRF is more appropriate than LA-ICP-MS.