Data for "Nitrate Preconcentration for Isotope Analysis of Dilute Environmental Samples: Application to Ice-Core Meltwater"

This dataset supports the study “Nitrate Preconcentration for Isotope Analysis of Dilute Environmental Samples: Application to Ice-Core Meltwater.” The study evaluates nitrate recovery and preservation of nitrogen (δ¹⁵N) and oxygen (δ¹⁸O) isotope composition during heating to dryness, vacuum centrifugal evaporation, off-line anion-exchange solid-phase extraction (SPE), and ion chromatography coupled with fraction collection. Files are organized by manuscript figure and associated tables. They include available measurements and summaries of nitrate recovery and isotope offsets, NaCl-addition experiments, reagent and procedural blanks, calibration and independent quality-control results, and calibrated nitrate isotope measurements for 20 Ross Ice Drainage System ice-core sections from RIDS95A and RIDS95B. Preliminary Δ¹⁷O measurements from 16 additional RIDS95A sections inform the correction and uncertainty propagation for δ¹⁵N. The dataset also includes conditional calculations examining how sample injections, calibration replication, hypothetical additional reference materials, and procedural blanks affect reported uncertainty or blank contributions. These design projections are modeled scenarios rather than experimentally validated performance. The accompanying README describes file contents, units, data sources, calculation assumptions, and limitations. Reported isotope intervals account for the specified calibration and repeatability contributions and, for δ¹⁵N, uncertainty in the estimated Δ¹⁷O correction; they do not represent complete procedural uncertainty.