Determinação de trihalometanos por HS-GC-MS em bebedouros do Centro de Ciências da Universidade Federal do Ceará

Abstract

Trihalomethanes (THMs) are one of the most prevalent classes of disinfection byproducts (DBPs) present in treated water. Four THMs are regulated by several countries in drinking water: trichloromethane (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and tribromomethane (TBM). Since these compounds often occur simultaneously, they are typically regulated as a group, known as total trihalomethanes (TTHMs). In Brazil, the maximum permitted value (MPV) for TTHMs in drinking water is 100 µg L⁻¹, as established by Ordinance GM/MS No. 888, dated May 4, 2021, which defines water potability patterns for human consumption. THMs are volatile species that can be efficiently determined using the headspace (HS) technique. A fast and direct method for the simultaneous determination of the four THMs in water samples using HS coupled with gas chromatography-mass spectrometry (GC-MS) was applied. The calibration curve parameters indicated good method performance, with linear responses (R > 0.99 for all THMs), low limits of detection (LD) and quantification (LQ), with LD ranging from 0.10 to 0.15 µg L⁻¹ and LQ between 0.30 and 0.47 µg L⁻¹, demonstrating satisfactory sensitivity and high selectivity confirmed by mass spectra. The method was applied to water samples from 18 drinking fountains located at the Science Center of the Federal University of Ceará. Results revealed that 50% of the samples analyzed exceeded the MPV for TTHMs. In all samples, the TCM was the predominant compound. The highest TTHMs concentrations exceed VMP by over 100%, highlighting the importance of monitoring these compounds to ensure water safety consumed by the academic community.