XRF Trace analysis

CSIRO bulk XRF methods routinely detect most elements to ~0.005wt%. The REE have typically higher detection limits in the order of 0.01wt%. Uranium and Thorium detection limits are pushed lower to ~0.002wt%. U & Th are included in REE, Ilmenite/Rutile and Zircon/Zirconia calibrations.

The halides are not easily measured by ICP-OES and must be available as the F^–, Cl^–, Br^– and I^– ions for electrochemical or titrimetric analysis. Salts of the halides are also quite volatile and lost during thermal decomposition. XRF is routinely used to determine the Cl, Br and I at trace levels (10-20ppm) in polymers, carbon and graphite. Fluorine can also be analysed by XRF but is less sensitive and higher detection limits result.

A modified Bruker scanning calibration is currently used to analyse graphite for trace elements across the periodic table.

Typical elemental sensitivity with ICP-OES provides a solution detection limit in the order of 20ug/L. Depending upon the dilution factor of the solid, this can translate to detection limits lower than achievable by XRF.