Dual capillary ion chromatography-mass spectrometry for the analysis of inorganic and organic ions in a high-resolution Antarctic ice core: Concentrations, trends, and synergies

• Dual capillary IC-MS method using only 190 µL of ice core sample • Multi-target quantification of 26 inorganic and organic ions • Targeted and untargeted screening enabled by mass spectrometry • High-resolution ice core records from Law Dome, Antarctica (2011-2021) • A powerful tool for exploring proxy source synergies A dual capillary ion chromatography-mass spectrometry (Cap IC-MS) method was developed and validated for the simultaneous determination of 26 inorganic and organic ions in Antarctic ice cores using only 190 µL of sample per analysis. The method combines capillary ion chromatography separation with suppressed conductivity and mass spectrometric detection to maximise selectivity, sensitivity, and analytical coverage, and demonstrated excellent limits of detection and repeatability, making it ideally suited for ice core studies. A total of 259 ice core samples from Dome Summit South (Law Dome, East Antarctica), spanning 2011–2021 at sub-monthly resolution, were analysed. Method performance was further evaluated against a validated standard ion chromatography approach using Passing–Bablok regression, showing strong agreement for most analytes, with minor systematic or proportional biases for a few species likely linked to calibration differences. Seasonal concentration profiles captured expected variability, including summer maxima in methanesulfonic acid and bromine enrichment reflecting marine biogenic activity and episodic enhancements in biomass-burning tracers, such as vanillic acid and p-hydroxybenzoic acid. By enabling the simultaneous quantification of halogens, major ions, and organic acids from a single sample, this Cap-IC-MS method minimises sample consumption, maximises chemical coverage, and provides a robust platform for paleoclimate and environmental reconstructions from precious Antarctic ice core archives.