Freon Improves Laser-Ablation Spectrometry

To reduce the incidence of elemental fractionation and improve the accuracy of laser ablation induction-coupled plasma mass spectrometry for the isotopic analysis of geological samples, Takafumi Hirata of Tokyo Institute of Technology suggests the addition of a refrigerant. In the Jan. 15 issue of Analytical Chemistry, the researcher reported that the delivery of Freon gas to laser ablation sites improves the precision of measurements of the ²⁰⁶Pb/²³⁸U ratio in ancient rocks.

Typically, the laser systems increase the Pb/U ratio by 20 to 50 percent as measurement progresses. Hirata found that exposing the ablation sites to 60 µl/min of Freon gas during the process offered a precision of 2 to 4 percent for the 1 billion-year-old and 2.4 billion-year-old zircon standards used in the experiment.