Utilization of Multiple Separation and Ionization Techniques on a Single High Resolution Mass Spectrometer for Comprehensive Screening of Environmental Water Samples with a Focus on Perfluoralkyl Substances

Oral Presentation

Prepared by K. Rosnack1, M. McCullagh2, G. Cleland1, L. Mullin1, J. Burgess1, A. Ladak1
1 - Waters Corporation, 34 Maple Street, Milford, MA, 01757, United States
2 - Waters Corporation, Stamford Avenue, Altrincham Road, Wilmslow, UK, SK9 4AX, United Kingdom

Contact Information: ken_rosnack@waters.com; 508-482-4639


Companies and regulatory authorities are under pressure to develop screening methods capable of detecting a broad spectrum of contaminants in a single analytical run. Many are turning to High-Resolution Mass Spectrometry (HRMS). Improvements in sensitivity and the highly selective acquisition techniques allow users to expand the scope of current targeted screening methods, as well as look for unknown or non-targeted compounds. Modern, non-targeted, HRMS screening methods are capable of collecting accurate mass spectra, with isotopic fidelity, for both precursor and product ions in a single injection with sufficient points across a UPLC chromatographic peak to perform quantification. Emphasis must now be placed on informatics to process and interrogate these comprehensive datasets.

Here, we demonstrate how several chromatographic and ionization techniques in combination with ion mobility and modern informatics can be used to comprehensively screen environmental water samples, including legacy and emerging perfluorinated compounds.

HRMS was coupled with multiple chromatographic techniques and ionizing methods (ESI and APGC) to expand the scope of the screening. The system was operated such that accurate mass precursors and accurate mass products were acquired in the same injection. Apex 3D peak picking algorithm and componentization were used to process and review data. A target list of compounds was screened using criteria such as retention time, mass error, isotopic fidelity and accurate mass fragment presence. In addition, and without the need to reprocess raw data, non-targeted (unknown) masses were also assessed using software discovery tools.

Collisional cross section (CCS), a unique measurement derived from ion mobility separation, allowed additional criterion for the search of targeted analytes. Ion mobility provided an additional dimension of separation which increased overall peak capacity and system resolution. The added peak capacity and spectral cleanup not only increased selectivity and confidence in the target matches but also simplified spectra for non-targeted (unknown) masses of interest.