Non-target analysis (NTA) employing high-resolution mass spectrometry is a commonly applied approach for the detection of novel chemicals of emerging concern in complex environmental samples. NTA typically results in large and information-rich datasets that require computer aided (ideally automated) strategies for their processing and interpretation. Such strategies do however raise the challenge of reproducibility between and within different processing workflows. An effective strategy to mitigate such problems is the implementation of inter-laboratory studies (ILS) with the aim to evaluate different workflows and agree on harmonized/standardized quality control procedures. Here we present the data generated during such an ILS. This study was organized through the Norman Network and included 21 participants from 11 countries. A set of samples based on the passive sampling of drinking water pre and post treatment was shipped to all the participating laboratories for analysis, using one pre-defined method and one locally (i.e. in-house) developed method. The data generated represents a valuable resource (i.e. benchmark) for future developments of algorithms and workflows for NTA experiments.
To close the "analytical gap" in the liquid chromatographic (LC) analysis of highly polar substances, two techniques which have been suggested earlier were tested in terms of retention factors and detection limits: hydrophilic interaction liquid chromatography (HILIC) and mixed-mode chromatography (MMC). A substance mix of 55 analytes ranging from logD − 8.2 to 3.4 and 17 different LC columns, also comprising additional reversed-phase columns were used. Contrary to most reversed-phase columns, column bleed has been identified as an important factor, which may cause serious restrictions during high-resolution mass spectrometric detection (HRMS). We found that highly abundant background masses continuously eluting from the columns heavily influence ion transmission to the detector. As a result, the linear dynamic range as well as the sensitivity decreases and thus limits the HRMS applicability of some columns. We therefore recommend a thorough investigation of ion transmission during HRMS method development. This will help to maintain the high potential of HRMS in terms of qualitative and quantitative screening analysis.
Analyte transformation post-sample collection can introduce uncertainty and reduce the reproducibility and reliability of results during the non-targeted analysis (NTA) of environmental samples. Understanding the type and degree of information lost is critical for accurate interpretation of the experimental results. Changes in the NTA feature profile of a sample were assessed over the immediate-toshort term (i.e., the first 24 and subsequent 120 h) to determine how much information is lost or changed. A wastewater sample was analyzed within 90 min of collection using liquid chromatography coupled to a high-resolution mass spectrometer. The sample remained in the cooled autosampler and was re-analyzed 47 times over 24 h and daily over the following 5 days (n = 15 data points). Detected features were classified as "formed," "increased," "unchanged," "decreased," or "eliminated." During the first 24 h, 7.4% of detected features underwent transformation, increasing to 58% over the following 5 days. Simultaneously analyzed aliquots kept at ambient temperature showed changes for 67% of the features. 86 features were (tentatively) identified, including one formed after sample collection. This shows that even on a short-term scale, considerable amounts of information can change or be lost while conducting NTA, potentially affecting reproducibility and reliability.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.