10.1021/ac504545w.s001 Daniel A. Deeds Daniel A. Deeds Avik Ghoshdastidar Avik Ghoshdastidar Farhad Raofie Farhad Raofie Élise-Andrée Guérette Élise-Andrée Guérette Alain Tessier Alain Tessier Parisa A. Ariya Parisa A. Ariya Development of a Particle-Trap Preconcentration-Soft Ionization Mass Spectrometric Technique for the Quantification of Mercury Halides in Air American Chemical Society 2015 technique mercury chloride Mercury Halides Current technologies chemical speciation mercury compounds ionization mass meter air HgX 2 mercury bromide future research trace measurements mercury halides 2015-05-19 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Development_of_a_Particle_Trap_Preconcentration_Soft_Ionization_Mass_Spectrometric_Technique_for_the_Quantification_of_Mercury_Halides_in_Air/2165527 Measurement of oxidized mercury, Hg­(II), in the atmosphere poses a significant analytical challenge as Hg­(II) is present at ultra-trace concentrations (picograms per cubic meter air). Current technologies are sufficiently sensitive to measure the total Hg present as Hg­(II) but cannot determine the chemical speciation of Hg­(II). We detail here the development of a soft ionization mass spectrometric technique coupled with preconcentration onto nano- or microparticle-based traps prior to analysis for the measurement of mercury halides in air. The current methodology has comparable detection limits (4–11 pg m<sup>–3</sup>) to previously developed techniques for the measurement of total inorganic mercury in air while allowing for the identification of HgX<sub>2</sub> in collected samples. Both mercury chloride and mercury bromide have been sporadically detected in Montreal urban and indoor air using atmospheric pressure chemical ionization-mass spectrometry (APCI-MS). We discuss limitations and advantages of the current technique and discuss potential avenues for future research including quantitative trace measurements of a larger range of mercury compounds.