For estimating the changes occurring in FAA availability in WM subjected to UV-A irradiation, WM was irradiated at medium (279 mJ/cm 2 ) and high doses (838 mJ/cm 2 ) and, compared with control (0 mJ/cm 2 ). From the WM samples FAA were extracted using Strata-X 33µm polymeric reversed-phase (200mg/3ml) cartridge (Phenomenex®, USA). The cartridge was initially conditioned with 3 ml of methanol and equilibrated with 3ml of water. Six milliliters of diluted (1:2) sample was loaded (1 ml/min) on to the catridge and extracted under vacuum at a slow and steady phase. Once the sample had completely passed through the cartridge, it was washed with 3ml of 5% methanol followed by 10mins drying. Finally, the FAA were eluted with 3ml of 5% ammonia in methanol and filtered with 0.2 μm PTFE before analysis.