Assessment of the autoxidation mechanism of p-toluenediamine by air and hydrogen peroxide and determination of mutagenic environmental contaminant in beauty salon effluent.

The present work investigated the autoxidation reaction of p-toluenediamine (PTD) - a precursor - widely used in permanent hair dyeing formulation, under experimental conditions close to the hair dyeing process (oxygen and/or peroxide in ammoniacal medium), by chromatographic and spectroscopic techniques. In additional, evaluated the mutagenicity of the PTD oxidation products and the presence of PTD and this products in wastewater from beauty salon, as well as in surface water and drinking water using HPLC coupled to a diode array detector and linear scan voltammetry. Through this study, it was possible the identification of semi-quinonediimine, quinonediimine, dimers (derived from toluenediamine), and trimer radical identified as Bandrowski's Base derivative (BBD) formed during autoxidation of PTD. Salmonella Typhimurium YG1041 assay with and without metabolic activation induced rat-liver (S9) indicated mutagenic activity for BBD. Levels of PTD were determined by the standard addition method in samples collected from the wastewater of a beauty salon, as well as from the water before and after treatment in a drinking water treatment plant (DWTP) reached concentrations of 2.08 ± 0.21, 2.36 ± 0.10 × 10-3, and 1.77 ± 0.13 × 10-3 mg L-1, respectively. In addition, linear sweep voltammetry was used to monitor the BBD found at the concentration of 1.59 ± 0.35 mg L-1 in wastewater collected from the beauty salon.