The Electron Capture Detector (ECD) on the Clarus 500 Greenhouse Gas Chromatograph (GC) at Weybourne Atmospheric Observatory is used to make quasi-continuous measurements of nitrous oxide (N2O) and sulphur hexafluoride (SF6) in atmospheric air. Samples are analysed every ten minutes and with reference to the NOAA2006A scale for N2O and NOAA2006 scale for SF6. In addition the instrument can determine the N2O and SF6 concentrations in discrete samples (i.e. whole air samples, SilcoCans). The measurements from this instrument are part of the National Centre for Atmospheric Science (NCAS) Atmospheric Measurement Facility (AMF) long-term measurement strategy.