Mercury species (iHg and MeHgþ) were separated in an analytical RP-C18 column (ODS Hypersyl
250 mm 4.6 mm id, 5 mm, Thermo Hypersil-Keystone). After separation, a photo-oxidation step was performed in a 12 meterlong 0.5mmid PTFE tube coiled around a UV lamp with 150W of power irradiation (Heraeus TQ 150)