HPLC–MSn and GC–MS methods to study sunlight and UV-lamp degradations of 1-amino-5-naphthalene sulfonate Original Research Article

HPLC–DAD, HPLC–MS/MS, GC–MS and spectrophotometric methods are employed to investigate the degradation process of sodium 1-amino-5-naphthalene sulfonate (1A5NS) aqueous solutions, when exposed to sunlight and UV-lamp (254 nm) irradiations. Experimental results show that both sunlight and 254 nm UV-lamp irradiations destroy the chemical and give rise to major degradation products, characterised by the same m/z ratios. Degradation times are lower for sunlight irradiation, for which a t1/2 value of 137.4 min has been evaluated, in comparison with the value of t1/2 of 26.8 min, observed for UV-lamp irradiation. The degradation pathway and the structures of the degradation products are proposed.