Benzotriazole and 5-methylbenzotriazole in recycled water, surface water and dishwashing detergents from Perth, Western Australia: analytical method development and application

Abstract

A simplified and sensitive liquid chromatography mass spectrometry (LC-MS) method without requiring sample pre-concentration was successfully developed for detecting the occurrence of ultra-low (ng L⁻¹) concentrations of benzotriazole (BTri), and its derivative 5-methyl benzotriazole (5-MeBT) in various Western Australian environmental water samples. The method detection limit was 2 ng L⁻¹, providing similar detection limits to other more process intensive methods where pre-concentration using solid phase extraction (SPE) was employed. The method was used to assess the occurrence of BTri and 5-MeBT in wastewater and surface water samples. Over a period of 12 months, BTri and 5-MeBT concentrations in secondary treated wastewater were measured, with the highest BTri and 5-MeBT concentrations observed during winter months at 78 ng L⁻¹ and 21 ng L⁻¹, respectively. The method was also used to assess the removal efficiency of BTri and 5-MeBT through an advanced water recycling plant (AWRP). While BTri was more persistent than 5-MeBT, both compounds were removed from the AWRP to <10 ng L⁻¹ (BTri) and <2 ng L⁻¹ (5-MeBT), with reverse osmosis (RO) providing the most effective treatment process for their removal.