How solid phase extraction conditions affect suspect and non-target screening for the evaluation of surface water contamination
Résumé
Identifying organic contaminants present in aquatic environments is of major concern for water quality
monitoring. New analytical and data treatment tools have been developed to meet this challenge. The
sample preparation before analyses is the first crucial step to be optimized before using suspect and nontarget-
screening approaches for qualitative evaluations of water pollution by contaminants from various
chemical and usage families.
As part of the action of Aquaref (www.aquaref.fr, French reference laboratory for environmental
monitoring in the Water Framework Directive), different solid phase extraction conditions (SPE, n=3 per
condition) were tested towards ultrahigh pressure liquid chromatography hyphenated to high resolution
mass spectrometry (UHPLC-HRMS) analysis. The SPE protocols varied according to the extraction phase
(Oasis HLB or multilayer cartridge), the elution solvent (methanol or methanol and dichloromethane)
and sample pH (pH 3 or 7). To ensure data quality, blank solvents, extracted blanks and quality control
(QC) were also injected. The QC sample corresponds to a pool of 5 μL of each sample extract and is
injected repeatedly throughout the injection sequence to monitor the analytical repeatability.
By suspect screening strategy, most of the investigated compounds were found in all SPE extracts. The
results revealed the presence of contaminants such as pesticides, pharmaceuticals, sweeteners, or anticorrosive
agents. For pesticides, approved (e.g. diuron) and not approved (e.g. terbutryn) compounds
were both detected. Concerning the pharmaceuticals, drugs acting on the nervous system were most
common (e.g. oxazepam), as well as betablockers (e.g. metoprolol). The without any a priori non-target
approach highlighted that the SPE conditions affect the quality and the interpretation of the data. For
each sample preparation method tested the number of signals (features) detected varies, as does the
number of signals associated with background noise.