Ions and organic acids were quantified in 7 aerosol samples collected during the Arctic campaign at Gruvebadet Laboratory in 2015. 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).