Rapid processing of 85Kr/Kr ratios using Atom Trap Trace Analysis

Abstract We report a methodology for measuring 85 Kr/Kr isotopic abundances using Atom Trap Trace Analysis (ATTA) that increases sample measurement throughput by over an order of magnitude to six samples per 24 h. The noble gas isotope 85 Kr (half‐life = 10.7 years) is a useful tracer for young groundwater in the age range of 5–50 years. ATTA, an efficient and selective laser‐based atom counting method, has recently been applied to 85 Kr/Kr isotopic abundance measurements, requiring 5–10 μL of krypton gas at STP extracted from 50 to 100 L of water. Previously, a single such measurement required 48 h. Our new method demonstrates that we can measure 85 Kr/Kr ratios with 3–5% relative uncertainty every 4 h, on average, with the same sample requirements.