In this poster, Picarro shares research and recommended best practices for using Picarro water isotope analyzers to measure highly enriched and depleted δ²H water isotope samples. These tips will be especially helpful for hydrological tracer studies and kinesiological applications. The experiments show how the Picarro water isotope analyzers’ Express Mode helps to address the memory effect and the spectroscopic limits of the analyzer without compromising precision, accuracy, or throughput time.