Session: Challenges of Non-target Screening in Water Analysis

Session Chair: Dr. Wolfgang Schulz, Dr. Christian Zwiener

Automated near real time HRMS quality assurance

Dr. Tobias Bader, Zweckverband Landeswasserversorgung
Nontargeted approaches based on liquid chromatography high-resolution mass spectrometry (LC-HRMS) are widely used in different fields of analytical chemistry. [1] Despite the widespread application of HRMS, sufficiently harmonized and recognized quality assurance (QA) practices are scarce. [2, 3] While QA is a key aspect to control and maintain data quality, it is often perceived a burdensome and time-consuming process. The objective of this work was thus to implement an automated near real time QA procedure to control the HRMS instruments in our lab. For all instruments, a recalibration by infusion of a reference solution is performed after every forth LC-HRMS run. After acquisition, these calibration files were automatically processed and used to extract time series data on i) mass accuracy, ii) resolving power and iii) signal intensity for both MS1 and MS2. Based on historical data, we set upper and lower thresholds for each of these parameters. Moreover, the standard deviation within the current batch was found to be a valuable problem indicator. If any tolerance limits were exceeded, the user is directly notified via email, which allows a timely initiation of measures. This approach leads to a reduction of the manual workload, while still maintaining a comprehensive QA. We could show that the automated QA allows the sensitive recognition of deviations, variations and creeping trends whereas the thorough compilation of QA data strongly supports the identification of problematic areas and is a great help for service engineers.
22-Jun-2022 12:30 (30 Minutes) ICM/Hall 3

Automated real time screening of organic pollutants in the water cycle using the transportable Orbitrap platform 'MS2field'

Heinz Singer, Eawag
Concentrations of organic micropollutants in the aquatic environment are often subject to strong, temporal fluctuations depending on sources, input pathways and transformation processes. These strongly varying concentration patterns can only be recorded with considerable effort using conventional sampling techniques. In addition, labile compounds often can not be transported and stored without loss until analysis in the laboratory. These deficits can be circumvented by on-site measurements. Nowadays, high-resolution mass spectrometry coupled with liquid chromatography is the method of choice for the sensitive and comprehensive analysis of known and unknown trace substances. In order to combine the advantages of this analytical technique with on-site measurement, a Q-Exactive HF mass spectrometer with a cross-flow filtration system, an automated solid phase extraction system and a liquid chromatograph was installed in a field-deployable trailer. This transportable ‘MS2field’ platform enables the acquisition of full scan mass spectra and data-dependent or data-independent MS2 in polarity switching mode over a 20min LC run. The analysis is fully automated and allows autonomous operation in the field. A programmable logic controller connected to multiple sensors, a surveillance camera, and remote internet access enable monitoring of the system and failsafe operation. Measured LC-HRMS files are automatically processed and the results transferred immediately to an online platform with a live view for selected compounds. [1] To demonstrate the performance of the developed platform under field conditions, measurements in a wastewater treatment plant and in surface water bodies will be presented. In total more than 10,000 measurements were acquired so far with the MS2field platform at the investigated field sites. Examples will be provided to illustrate how these large data sets were processed for target and non-target compounds released from various sources (industry, residential area, agriculture) in the watershed.
22-Jun-2022 13:00 (30 Minutes) ICM/Hall 3

NTS approaches for PFAS in soil samples

Dr. Boris Bugsel, Universität Tübingen
The class of poly- and perfluorinated alkyl substances (PFAS) comprises more than 3000 compounds which have a broad application area, from industrial processes to consumer products. For example, PFAS are used to produce paper and card board with water and grease repelling properties. Paper sludge from impregnated paper products was presumably applied on agricultural soils during a period of ten years and caused contamination of several millions of square meters on a site in southwest Germany. Since no information is available on the identity of the contaminants, analytical screening approaches have to be used to characterize the contamination. Original PFAS chemicals and their transformation products have been identified in soil samples by liquid chromatography-high-resolution mass spectrometry (LC-HRMS) screening approaches [1]. Data analysis comprised Kendrick mass defect analysis and systematic retention time shifts to assign homologous series and matching with a suspect list. LC-HRMS analysis of contaminated soil samples identified a total of 65 individual substances from 13 different substance classes. In particular, the substance class of disubstituted perfluoroalkyl phosphates (diPAPs) as well as their transformation products could be identified as major contaminants. PFAS distribution patterns in contaminated soil samples have further been compared with PFAS distribution patterns in impregnated papers collected at about the same time as the contamination occurred. The results confirm the hypothesis that impregnated papers are major sources of the contamination [2]. Environmental processes have been mimicked by photochemical and electrochemical experiments which demonstrated that commercially used PFAS are slowly converted to transformation products (TPs, e.g. perfluoroheptanoic acid from 6:2 diPAP [3]) which are affecting the groundwater quality in the long term.
22-Jun-2022 13:30 (30 Minutes) ICM/Hall 3

NTS on its way to international standardization

Dr. Michael Petri, Zweckverband Bodensee-Wasserversorgung
In the last decade non-target screening (NTS) with high performance liquid chromatography and high resolution mass spectrometry (HPLC-HRMS) has become a very powerful analytical tool to detect and identify organic pollutants in the aqueous environment, that have not been detectable with the common approach of target analytic methods. A continual research and development in research institutes and analytical companies has improved the capabilities of the analytical hardware and software with statistic tools for an efficient post-acquisition data treatment for prioritization of unknown compounds and for their elemental and structural elucidation. NTS is now leaving the highly sophisticated world of research institutes to enter the area of routine laboratories. But is NTS really ready for the routine analytics? NTS it still a challenging analytical tool and needs a lot of things to keep in mind. 2019 the German Water Chemistry Society and 2021 the Royal Netherlands Standardization Institute published guidelines for the usage of non-target screening in water analysis [1, 2]. Both guidelines have defined general prerequisites and requirements for NTS in water analysis and set a special focus on general quality measurements and criteria to ensure comparable and reliable results for NTS in water analysis. NTS has been used successfully for monitoring, detection and identification of emerging compounds their metabolites, transformation and degradation products in environmental water samples An international standardization will be the next consistent step to give NTS a better acceptance by administrations and routine laboratories as a powerful monitoring tool for environmental samples. The published NTS-guidelines [1, 2] are a very sound basis for an international standard. An ISO standard developed for NTS will help to encourage routine laboratories and authorities to introduce NTS as a useful analytical tool to detect and identify emerging compounds in environmental samples.
22-Jun-2022 14:00 (30 Minutes) ICM/Hall 3