Aquatic phototransformation study of the antifouling agent Sea-Nine 211: identification of byproducts and the reaction pathway by gas chromatography–mass spectroscopy

The photochemical behaviour of the biocide Sea-Nine 211 was carried out in order to investigate several transformation products formed in different environmental matrices and under different conditions. Sea-Nine 211 photodecomposition was performed under laboratory conditions using a xenon light source and under natural sunlight conditions in sea, river, lake as well as in distilled water. In order to examine the effect of dissolved organic matter (DOM), the phototransformation of the tested biocide was studied also in the presence of various concentrations of humic and fulvic acids. The phototransformation was shown to proceed via pseudo-first-order reaction in all cases and the presence of humic and fulvic acids enhanced the photolysis reaction. Kinetic experiments were monitored with GC–ECD and the half-lives (t1/2) varied between 6 and 433 h. Irradiation of the aqueous Sea-Nine 211 solutions gave rise to a great number of transformation products that were isolated by means of SPE using SDB extraction disks while six of them were tentatively identified using GC–MS techniques. Based on this byproduct identification a possible transformation pathway is proposed for the decomposition of Sea-Nine 211 in aqueous media.