The Aerodyne Quadrupole Aerosol Chemical Speciation Monitor
(ACSM) instrument operated by King's College London for the Clearflo project is similar in function to the related Aerosol Mass Spectrometer, but is optimised for long-term monitoring, with a lower specification of mass spectrometer and no sizing capability. Aerosol are drawn into the instrument through an aerodyamic lens and concentrated using differential pumping, before being vaporised at 600 °C on a tungsten surface. The vapors are then analysed using 70 eV electron ionisation, the output is then Aerosol non-refractory mass concentrations and mass spectra of Nitrate, sulphate, ammonium, particulate organic matter,
particulate organic source apportionment at a frequency of approx 30 minutes. This is the same instrument as the KCL ASCM but processed further.