**Preface to "(Mass Spectrometric) Non Target Screening–Techniques and Strategies"**

Mass spectrometric non-target screening is a preferably comprehensive and untargeted (predominantly organic molecules detecting) approach combining (robust) analytical measurements with adapted data evaluation concepts, systematic compound identification workflows, and statistical data interpretation. It is well suited for the identification of new, unexpected, and/or unknown organic compounds, as well as monitoring 'molecular fingerprints'and profiling 'process-relevant'molecules via statistical methods.

Non-target screening (NTS) provides special benefits for the investigation of complex samples in various disciplines. Even well-characterized samples can contain relevant and yet not detected compounds. Depending on the nature of the sample and the aim of the analytics, the presence of such unknown compounds can be of concern and relevance. Non-target screening is a universal technique that can be applied in many areas, such as environmental, forensic, food, metabolomics and other analysis. Since several meetings in 2016 (and later) regarding that topic, and many books and publications, the NTS topic has gained a new level of knowledge and awareness. A lot of this knowledge was presented on face-to-face, hybrid, and digital conferences and workshops, such as the 'International Conference on Non-Target Screening' and the 'Gas Chromatography meets Non-Target Screening' (details regarding the programs and others see on https://afin-ts.de). Further, many of which presenting there also published in these years in this special NTS issue.

Concluding, in the years 2019–2022, 14 articles were published and presented in this Special Issue, whereby it contains 4 peer-reviewed review articles and 10 peer-reviewed research articles. The focus of the review articles is on semi-quantitative NTS (Malm et al.), on GC-IMS (Capitain and Weller), on GC-API-MS (Li et al.) and on liquid biomarkers (for Equine anti-doping (Tou et al.). Two research articles deal with analytical data processing concepts (Rubino and Yang et al., respectively) and eight research articles present strategies in various disciplines. Hunynh et al. presented sample preparation methods for NTS in urban waters, Panse et al. water-solved molecules after UV photo dissociation, whereas Morimoto et al. studied the aqueous matrix tea and Stegmueller et al. human urine (after coffee consumption). Further metabolomics studies are presented by Satria at al. (in Lingzhi), Dionisio et al. (in Maize roots), and Xue et al. (in Lettuce as well as Maize). Last but not least, Alvarez et al. presented a glycomics-driven glycoproteomics analytical platform for unknown inhibitors.

All in all, this Special Issue is reflecting new NTS developments in the recent years and is at the same time a good starting point for the screening need of the forthcoming ones. If you are interested to publish your resent developments open-access do not hesitate to contact me for a publication in the next Special Issue.

> **Thomas Letzel** *Editor*
