Abstract Noble gases are valuable geochemical tracers for investigating subsurface fluid origins and migration because of their chemical inertness and source‐specific isotopic ratios. However, subsurface water samples often show noble gas patterns that differ from air‐saturated water references, with excesses or depletions that complicate interpretation. Air contamination remains a challenge, as it can distort noble gas signatures, particularly in complex fluid systems where mass‐dependent fractionation also occurs. This study evaluates current air correction techniques and proposes an enhanced workflow. We first tested how sample storage duration affects air contamination by comparing three container types: copper tubes, classical stainless steel cells, and specially designed stainless steel cells, using gas samples from Scotland. Next, we collected deep groundwater in situ for the first time for noble gas analysis from a hydrocarbon reservoir in Malaysia (>4 km) using wireline formation testers. This enabled us to develop a correction method that accounts for both air contamination and mass fractionation (MF). We analyze deviations in noble gas elemental ratios ( 20 Ne/ 36 Ar, 84 Kr/ 36 Ar, 132 Xe/ 36 Ar) relative to air by atomic mass units. The slope of these deviations helps identify water‐derived patterns, allowing correction for MF in groundwater samples, excluding mantle‐enriched fluids. Apparent excess neon in groundwater, when referenced to air‐saturated water, is effectively corrected using a first bubble pattern. An identified xenon depletion is managed using the first bubble framework (0–10°C). We propose a method to correct air contamination and MF, thereby enhancing noble gas analysis and supporting the study of fluids enriched with crustal‐produced noble gases.
Diniz et al. (Fri,) studied this question.