Evaluation of potential monazite reference materials for oxygen isotope analyses by SIMS and laser assisted fluorination

The δ18O values for the four studied monazites have been determined by laser fluorination (LF). They are as follows (1 SD): 1.5 ± 0.1‰ for Moacyr, 10.2 ± 0.1‰ for Manangoutry, 8.5 ± 0.2‰ for UNIL-Mnz1, and 9.5 ± 0.3‰ for the slightly less homogenous UNIL-Mnz2. The analytical protocol adopted here results in consistently high yields (> 90%) and reproducible values, and hence it is argued that LF is a viable method for the calibration of phosphate reference materials.