Chemical fate and mutagenic formation potentials of phenothiazine and related compounds during water chlorination

Abstract

-The reactions of hetero-tricyclic aromatic hydrocarbons (H-TCAHs) with hypochlorite in an aqueous solution were investigated under conditions that simulate wastewater disinfection. H-TCAH-hypochlorite reaction products were determined by gas chromatographic-mass spectrometric (GC-MS) analyses. For 20 µM, 10H-phenothiazine, 10H-phenoxazine, and phenoxathiin reacted rapidly with active chlorine in neutral pH (7.0), but no phenazine-hypochlorite reaction was observed over pH values of 5-9 for 1 hr. The 10H-phenothiazine-hypochlorite reaction began by oxidation with active chlorine to form its dioxides, followed by chloro-substitution in water. The extent of the reactions depended on the chlorine dose, solution pH and compound structures. Ames assays for the chlorination byproducts of 10H-phenothiazine and 10H-phenoxazine also showed to be weak mutagenicity in TA98 and TA100 strains without S9 mix, but no chlorination byproducts of phenoxathiin exhibited any mutagenicity in both tester strains with and without S9 mix.

Environmental Mass Spectrometry: Emerging Contaminants and Current Issues

“…Reaction pathways were also proposed. Chlorination products of phenothiazine and related heterotricyclic aromatic hydrocarbons were the focus of another study by Sekizawa and Onodera, who used GC/MS for their identification . Oxidation reactions began with the formation of dioxides, followed by chloro-substitution.…”

“…Chlorination products of phenothiazine and related heterotricyclic aromatic hydrocarbons were the focus of another study by Sekizawa and Onodera, who used GC/MS for their identification. 173 Oxidation reactions began with the formation of dioxides, followed by chloro-substitution. Two DBPs, 10Hphenothiazine and 10H-phenoxazine, were shown to be weak mutagens in the Ames assay.…”

Transformation Products of Emerging Contaminants upon Reaction with Conventional Water Disinfection Oxidants

“…Reprinted with permission from [54] Copyright (2006) American Chemical society. and the antacid drug cimetidine were shown to be degraded during chlorination treatments [44,47,49,55,56]. On the other hand, the angiotensin agent valsartan and the psychiatric drugs bromazepan, carbamazepine, chlorpromazine, phenytoin and venlafaxine survived chlorination [55].…”

“…For fluoxetine, only the N-chloramine product has been identified in the literature [47]. In the case of phenothiazine, the first step is oxidation to the sulfone, followed by chloro-substitution in either the amine or the aromatic rings [56]. The chlorination pathway of oxcarbazepine proceeded by mono-and di-chlorination at the a-carbon to the carbonyl group, followed by hydrolysis and formation of a new carbonyl group and, finally, ring enclosure by an intramolecular reaction to produce a quinazoline moiety [44].…”