Potential aerosol mass (PAM) chamber used to investigate the oxidised products from the photo-oxidation of m-xylene and toluene. The chamber experiments are carried out with hydroxyl (OH) radical as oxidant in both high- and low-NOx conditions and the resultant aerosol samples were collected using quartz filters and analysed by the two dimensional Gas Chromatography Time-Of-Flight Mass Spectrometry (GC×GC-TOFMS) at the University of Birmingham.