Ions and organic acids were quantified in 46 aerosol samples collected during the Arctic campaign at Gruvebadet Laboratory in 2018 and 2019. Aerosol samples were collected in quartz fiber filters. They were spiked with isotopically labelled standard solutions (2 - 3 µg/ml) prior extraction. Ion and organic acid content was measured using IC-MS and HPLC-MS.

Extraction of ions and organic acids, with exception of pinic and pinonic acids, was done as follows: A quarter of the filter was broken into small pieces and placed in polyethylene tubes, using steel tweezers. Slotted filters were ultrasonically extracted for 30 min with 7 mL of ultra-pure water, while backup filters with 15 mL of ultra-pure water. Extracts were filtrated through a 0.45 μm PTFE filter to remove residues before the analysis. Determination and quantification of major ions and organic acids were performed using an IC-MS system.For the determination of pinic and pinonic acids a HPLC-MS/MS system was used.Values below the detection limit of the measurements are indicated (<0.xxxxx).