Ultra-high performance liquid chromatography–quadrupole time-of-flight mass spectrometry to identify contaminants in water: An insight on environmental forensics

Abstract

Ultra-high pressure liquid chromatography–quadrupole time-of-flight mass spectrometry (UHPLC–QqTOF-MS) acquiring full scan MS data for quantification, and automatic data dependent information product ion spectra (IDA-MS/MS) without any predefinition of the ions by the user was checked for identifying organic contaminants in water samples. The use of a database with more than 2000 compounds achieved high confidence results for a wide number of contaminants based upon retention time, accurate mass, isotopic pattern and MS/MS library searching. More than 20 contaminants, mostly pharmaceuticals, but also mycotoxins and polyphenols were unambiguously identified. Furthermore, the combination of statistical data analysis using principal component analysis (PCA) followed by empirical formula calculation, on-line database searching and MS/MS fragment ion interpretation achieves not only the successful detection of unknown contaminants but also the selection of those relevant to different types of waters. Unknown compounds, such as C20H34O3, were identified in waste water showing the prospects of this technique. A group of 42 currently used pesticides were selected as target compounds to evaluate the quantitative possibilities. Mean recoveries and percentage relative standard deviation (RSD) were 48–79% (4–20% RSD). The limit of detections ranged from 0.02 to 2ngL−1, with a validated limit of quantification of 2ngL−1 for water after solid-phase (SPE) isolation and concentration. The quantitative data obtained using UHPLC–QqTOF-MS were compared with those obtained using conventional LC–MS/MS with a triple quadrupole (QqQ).