Holistic and Detailed View on Workflow Strategies Applied in This Book

Chapter 10

Downloaded by UNIV OF NEW ENGLAND on February 23, 2017 | http://pubs.acs.org Publication Date (Web): December 12, 2016 | doi: 10.1021/bk-2016-1242.ch010

Holistic and Detailed View on Workflow Strategies Applied in This Book Thomas Letzel* and Jörg E. Drewes Chair of Urban Water Systems Engineering, Technical University of Munich, 85748 Garching, Germany *E-mail: [email protected].

A final view on the analytical workflow strategies in this book revealed clear trends and common solutions in the identification and also quantification of chemicals of emerging concern (CECs) and associated transformation products (TPs). Although the questions asked, needs, tasks and motivations are very diverse while analyzing CECs and TPs in the aqueous environment, they reflect similar foci regarding the analytical LC-MS techniques used. LC-MS workflow strategies can be differentiated into the analysis of targets, suspects, hidden targets and unknowns. Several workflows make thereby use of the same sequence of working processes: a) the initial sampling and analysis that results in experimental data; b) experimental data is subsequently preprocessed which leads to specific datasets; c) the datasets can then –according to their specific focus- be used in the direction of quantitative (target) analysis, compound recognition (by suspects screening), compound finding (by hidden target screening) or the identification of unknowns. Various strategies are supported by vendor software and open access tools. This concluding chapter attempts to derive a holistic view through a systematic analysis of strategies in environmental analysis as well as strategies applied in other disciplines.

© 2016 American Chemical Society Drewes and Letzel; Assessing Transformation Products of Chemicals by Non-Target and Suspect Screening Strategies and ... ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


Disclaimer: The information in this chapter has been extracted from all chapters and is presented in schedule style without further discussion. Several terms, phrases and abbreviations used in the figures are defined in the captions or can be found in the subject index. Additional descriptions can be found in the individual chapters. Sometimes there were more definitions for the same process or fact. Thus, we have chosen the most appropriate terms in our opinion in order to provide some consistent language. However, we certainly encourage the reader to study all chapters and make your own decision on the most appropriate terms. Furthermore, in the subsequent Appendix, the individual authors of each chapter have extracted in their own style the workflow strategies they used or suggested. Thus, we attempted to provide here a holistic view summarizing the global processes and strategies, while not neglecting the individual solutions. The steps outlined in this visual summary are not always linear. Thus, the order can and does vary from time to time. On this note, we hope you enjoyed this book. It may help you to be effective in non-target screening (NTS) and to gain new valuable insights in this field.

Figure 1. General LC-(LC)-MS(/MS) workflows applied in this book. The structure consists of four (vertical) main workflow topics and four (horizontal) strategical subtopics. 176 Drewes and Letzel; Assessing Transformation Products of Chemicals by Non-Target and Suspect Screening Strategies and ... ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


Figure 2. Detailed workflows applied in this book. The ‘tasks’ contain three main topics (with subtopics, respectively) on which the book chapters are based on.

177 Drewes and Letzel; Assessing Transformation Products of Chemicals by Non-Target and Suspect Screening Strategies and ... ACS Symposium Series; American Chemical Society: Washington, DC, 2016.


Figure 3. Detailed experimental workflows applied in this book. The topic ‘Analysis’ consists of four (vertical) main working areas and four (horizontal) strategical subtopics in ‘Detection’. Please note that other samples, sample preparation, separation or detection strategies etc. can be found in the NTS workflows, but experimentally not realized in the chapters of this book. The horizontal detection strategies measuring ‘targets’ and ‘suspects’ (both left-hand side) make use of the so called multiple reaction monitoring (MRM) and other types of MS/MS fragment spectra observations. Typically this data can be maintained by several tandem mass spectrometers on the market. The detection strategies of ‘hidden targets’ and ‘unknowns’ (both right-hand side) typically make use of the so called non-target screening (NTS) observing molecule ions and/or MS/MS fragment spectra with accurate, high resolution (tandem) mass spectrometers (HRMS). Typically ‘suspects’ and ‘hidden targets’ are not differentiated; however, in this book one chapter (and references therein) describes the diverse technical strategies although the data set processing is sometimes similar (see also Figure 5). Each strategy finally results in ‘Experimental data’, respectively.



Figure 4. Detailed preprocessing workflows using ‘Experimental Data’ applied in this book. The topic ‘Targets’ contains three approaches. These approaches represent different types of quantitative analysis using reference standards. The topic ‘Suspects /Hidden Targets/ Unknowns’ contains five approaches with precise data preprocessing procedures. These procedures make use of chromatographic and mass spectrometric information resulting from one or more samples (with or without background measurements). Each workflow finally results in ‘Evaluated Data,’ respectively.



Figure 5. Detailed processing workflows using ‘Evaluated Data’ obtained in this book. The workflow topic ‘Targets’ is resulting in a compound quantification. The topics ‘Suspects’ and ‘Hidden Targets’ are described in more detail in Figure 6. The workflow topic ‘Unknowns’ can be split up into a) handling the unknowns without their identification (Prioritization of Unknown Compounds in Application) and into b) the try to identify the unknown molecule (Compound Identification). Each strategy finally results in ‘Answers’ according to the tasks, respectively.



Figure 6. Detailed processing workflows for ‘Suspect’ and ‘Hidden Target’ strategies using ‘Evaluated Data’ obtained in this book. The evaluated data for ’Suspects’ (i.e. search for expected compounds or ‘Compound Recognition’) as well as ‘Hidden Targets’ (i.e. search for ‘Known Unknowns’ or ‘Compound Finding’) can often be processed with the same theoretical tools or software. However, the technical and knowledge preconditions may differ. The manual data processing I) includes minimum five different subtopics for CECs and TPs. The sophisticated approach includes so far the subtopic ‘Advanced Workflow Platforms’. Each strategy finally results in ‘Answers’ according to the tasks, respectively.


Holistic and Detailed View on Workflow Strategies Applied in This Book

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