A simple polymer electrolyte membrane system for enrichment of low-level tritium (H) in environmental water samples.

Tritium (H) is an essential tracer of the Earth's water cycle; yet widespread adoption of tritium in hydrologic studies remains a challenge because of analytical barriers to quantification and detection of H by electrolytic pre-concentration. Here, we propose a simple tritium electrolytic enrichment system based on the use of solid polymer electrolyte membranes (PEMs) that can be used to enrich H in 250-3000 mL environmental water samples to a 10-mL final volume. The IAEA PEM-H system reported here can produce high enrichment factors (>70-fold) and, importantly, removes some of the deterrents to conventional H enrichments methods, including the use of toxic electrolysis and neutralization chemicals, spike standards, a complex electrolysis apparatus that requires extensive cooling and temperature controls, and improves precision by eliminating the need for tracking recovery gravimetrics. Preliminary results with varying operating conditions show H enrichments to 70-fold and higher are feasible, spanning a wide range of tritium activities from 5 to 150 TU with a precision of ∼4.5 %. Further work is needed to quantify inter-sample memory and to establish lower H detection limits. The IAEA PEM-H system is open source, with 3-D CAD and design files made freely available for adoption and improvement by others.