Non-target screening with high-resolution mass spectrometry: critical review using a collaborative trial on water analysis

Abstract

In this article, a dataset from a collaborative non-target screening trial organized by the NORMAN Association is used to review the state-of-the-art and discuss future perspectives of non-target screening using high resolution mass spectrometry in water analysis. A total of 18 institutes from 12 European countries analysed an extract of the same water sample collected from the River Danube with either one or both of liquid and gas chromatography coupled with mass spectrometric detection. This article focuses mainly on the use of high resolution screening techniques with target, suspect and non-target workflows to identify substances in environmental samples. Specific examples are given to highlight major challenges such as isobaric and co-eluting substances, dependence on target and suspect lists, formula assignment, the use of retention information and the confidence of identification. Approaches and methods applicable to unit resolution data are also discussed. While most substances were identified using high resolution data with target and suspect screening approaches, some participants proposed tentative non-target identifications. This comprehensive dataset revealed that non-target analytical techniques are already considerably harmonized between the participants, but the data processing remains time-consuming. Although the dream of a "fully-automated identification workflow" remains elusive in the short-term, important steps in this direction have been taken, exemplified in the growing popularity of suspect screening approaches. Major recommendations to improve non-target screening include better integration and connection of desired features into software packages, the exchange of target and suspect lists and the contribution of more spectra from standard substances into (openly accessible) databases.

Assessing the Exposome with External Measures: Commentary on the State of the Science and Research Recommendations

“…There is also a need for improved assessment of exposure variability, including minute, daily, and yearly variability, as well as peak and intermittent exposures, in multiple, critical life stages, including the targeted development of standardized external exposure metrics for use in utero, in early childhood, in adolescence, and in senescence (82,108). Analytical platforms based on high-resolution mass spectrometry have also been applied in quantitative and qualitative analysis of contaminants in various exposure matrices such as surface water and house dust (77,84). Coupling with different extraction and separation techniques, these highly sensitive analytical platforms not only enable quantitation of targeted contaminants but also allow for suspect screening and nontargeted analysis of environmental exposures based on how the data are processed (1).…”

Quantitative mass spectrometry methods for pharmaceutical analysis

“…As can be seen in recently published reviews, HILIC columns are much less frequently used in environmental studies. Most water analyses are still done using reversed-phase (RP) stationary phases and in particular C 18 columns [91,[102][103][104]. However, to allow the simultaneous analysis of polar and apolar compounds, both RP and HILIC columns can be combined.…”

“…However, to allow the simultaneous analysis of polar and apolar compounds, both RP and HILIC columns can be combined. In this way, highly polar substances are subjected to an improved separation and interferences will be spread more resulting in reduced MEs [104]. The coupling of orthogonal stationary phases is usually done with a T-piece or switching valves and a second pump to dilute the mobile phase of the first dimension post-column to make the eluate compatible with the second dimension separation [104][105][106].…”

“…In this way, highly polar substances are subjected to an improved separation and interferences will be spread more resulting in reduced MEs [104]. The coupling of orthogonal stationary phases is usually done with a T-piece or switching valves and a second pump to dilute the mobile phase of the first dimension post-column to make the eluate compatible with the second dimension separation [104][105][106]. Although it has not yet been used to analyse real water or biological samples, an alternative approach to couple HILIC and RP columns in series has recently been proposed [107,108].…”

Going Beyond the Analysis of Common Contaminants: Target, Suspect, and Non-Target Analysis of Complex Environmental Matrices by High-Resolution Mass Spectrometry

“…The data analysis usually includes steps such as peak-picking, blank subtraction, componentization, molecular formula generation, isotopic pattern comparison, evaluation of adducts, and the assessment and comparison of fragmentation patterns . The benefits of suspect and non-target analysis to screen for known and emerging contaminants and their transformation products have been extensively documented in the literature (Avagyan et al, 2016;Bletsou et al, 2015;Gago-Ferrero et al, 2015;Heuett, 2015;Ruff et al, 2015;Schymanski et al, 2015).…”