Development of a retrospective processing and data aggregation platform for non-target screening of surface waters

Abstract

Background

Data accessibility and exchange are current key topics in the exploitation of the enormous potential of non-target screening (NTS) for surface water monitoring, especially when monitoring water bodies crossing jurisdictional boundaries. So far, major challenges stem from (1) the size of NTS raw measurement files, (2) the diverse array of instrumental and computational methods, and (3) a need for continuous reprocessing of measurement files as spectral libraries grow. Pre-processing workflows connected to databases and online dashboards are one crucial way to address these challenges and provide direct access to monitoring data.

Results

The NTSPortal is a data assessment dashboard and repository for pre-processed and annotated NTS data for online access by users in the fields of analytical chemistry and environmental management. It provides both a graphical interface for search and visualization and a programming interface for integration into tailored data science workflows. We present the functionality using data from over 12,000 measurements from over 300 sampling sites within Germany analyzed with a uniform method over the course of 7 years. Using a collaborative spectral library, over 1000 compounds were identified via library screening, including pharmaceuticals, synthesis intermediates, and transformation products. We report performance figures and several use-cases demonstrating (a) searching for multiple substances and retrieving an overview of their detections in different matrices, (b) selecting a substance based on long-term intensity trends and visualizing time series, and (c) searching for substances with an isolated spatial occurrence pattern. The programming interface is demonstrated by implementing a time-series analysis script to search for discontinuous emission patterns.

Conclusions

The highly automated pre-processing workflow for library screening allows much of the “heavy lifting” in NTS data processing to be off-loaded, enabling the environmental manager to focus on data analysis. The proposed system is open source and institutional access to the database can be made available upon request. The database has a flexible schema geared towards surface water monitoring but can be adapted to different needs. Further development of the system is underway, including the integration of unknown non-target features (without a library match), different instrumental analytical methods and concentration estimates.