Real time measurement of PAN using SIFT-MS

The on-line detection of gaseous peroxyacetyl nitrate (PAN) using SIFT-MS has been investigated using a synthetic sample of PAN in air at a humidity of ~30%. Using the H3O+ reagent ion, signals due to PAN at m/z 122, 77 and 95 have been identified. These are the protonated PAN, protonated peractetic acid and its water cluster respectively. .These products and their energetics have been probed through quantum mechanical calculations. The H3O+ rate coefficient has been estimated to be 4.5x10-9 cm3 s-1 leading to a PAN sensitivity of 138 cps/ppbv. This gives a limit of detection of 20 pptv in 10 s using the m/z 122 product ion.