Agilent 7500 icp ms instrument

The samples were weighed (from 1.6 to 6.9 mg) and transferred in Fluorinated ethylene propylene (FEP) vials, previously washed to avoid any kind of external contamination. Regia solution was chosen for the mineralization as it combines the oxidizing capacities of HNO₃ with the complexing capacities of chlorides against I₂ produced during digestion. In particular, 750 µL of HCl and 150 µL HNO₃ were added and the solution was heated to 80 °C for 3 hours. The volume was adjusted to 5.0 mL and then diluted another 10 times before the ICP–MS analysis. The analysis was performed with an Agilent 7500 ICP–MS instrument (Palo Alto, CA, USA). Four standards at 10, 20, 50, and 100 ppb of iodine and gold were used for calibrating the instrument.

Total Hg (THg) concentrations were determined using a ThermoScientific (Germany) Element XR single-collector sector-field ICP-mass spectrometry instrument (SF-ICP-MS) working at low mass resolution, as was previously described by Rua-Ibarz et al.^{80 (link),81 (link)}. For QA/QC of the entire analytical procedure, three CRMs with similar matrix composition as those of the samples were analysed - BCR CRM 464 (tuna fish), NRC-CNRC DORM-4 (fish muscle) and TORT-3 (lobster hepatopancreas) – and the Hg recoveries obtained were between 93–107%.
Hg speciation was performed at the University of Aberdeen using a HP-6890 GC-unit (Agilent Technologies, Japan) coupled to an Agilent 7500 ICP-MS instrument (Agilent Technologies, Japan), as previously described by Gajdosechova et al.^{9 (link)}. The analytical method was validated using two CRMs – NRC-CNRC DOLT-2 and DORM-2. The results obtained were in agreement with the certified values (recoveries between 93–110%).