Mobile phase and column chemistry selection for high sensitivity non-targeted LC/ESI/HRMS screening of water

Amina Souihi; Miklos Peter Mohai; Jonathan W Martin; Anneli Kruve

doi:10.1016/j.aca.2023.341573

Mobile phase and column chemistry selection for high sensitivity non-targeted LC/ESI/HRMS screening of water

Anal Chim Acta. 2023 Sep 15:1274:341573. doi: 10.1016/j.aca.2023.341573. Epub 2023 Jun 28.

Authors

Amina Souihi¹, Miklos Peter Mohai¹, Jonathan W Martin², Anneli Kruve³

Affiliations

¹ Department of Environmental and Materials Chemistry, Stockholm University, Svante Arrhenius väg 16, 106 91, Stockholm, Sweden.
² Department of Environmental Science, Stockholm University, Svante Arrhenius väg 8, 106 91, Stockholm, Sweden; Science for Life Laboratory, Department of Environmental Science, Stockholm University, Svante Arrhenius väg 8, 106 91, Stockholm, Sweden.
³ Department of Environmental and Materials Chemistry, Stockholm University, Svante Arrhenius väg 16, 106 91, Stockholm, Sweden; Department of Environmental Science, Stockholm University, Svante Arrhenius väg 8, 106 91, Stockholm, Sweden. Electronic address: anneli.kruve@su.se.

PMID: 37455083
DOI: 10.1016/j.aca.2023.341573

Abstract

Systematic selection of mobile phase and column chemistry type can be critical for achieving optimal chromatographic separation, high sensitivity, and low detection limits in liquid chromatography electrospray high resolution mass spectrometry (LC/MS). However, the selection process is challenging for non-targeted screening where the compounds of interest are not preselected nor available for method optimization. To provide general guidance, twenty different mobile phase compositions and four columns were compared for the analysis of 78 compounds with a wide range of physicochemical properties (logP range from -1.46 to 5.48), and analyte sensitivity was compared between methods. The pH, additive type, column, and organic modifier had significant effects on the analyte response factors, and acidic mobile phases (e.g. 0.1% formic acid) yielded highest sensitivity. In some cases, the effect was attributable to the difference in organic modifier content at the time of elution, depending on the mobile phase and column chemistry. Based on these findings, 0.1% formic acid, 0.1% ammonia and 5.0 mM ammonium fluoride were further evaluated for their performance in non-targeted LC/ESI/HRMS analysis of wastewater treatment plan influent and effluent, using a data dependent MS² acquisition and two different data processing workflows (MS-DIAL, patRoon 2.1) to compare number of detected features and sensitivity. Both data-processing workflows indicated that 0.1% formic acid yielded the highest number of features in full scan spectrum (MS¹)^, as well as the highest number of features that triggered fragmentation spectra (MS²) when dynamic exclusion was used.

Keywords: Data dependent acquisition; Identification of unknowns; Ionization efficiency; Limit of detection; Method optimization.