Characteristic response of formulation ingredients revealed by ultra high performance liquid chromatography-electrospray ionization-high resolution mass spectrometry-based untargeted screening of pesticides in soil

Commercial solutions of pesticides consist of two main components: The active substance and the formulation ingredients. These ingredients, mainly composed of polymeric surfactants, are considered inert vis-a-vis the targeted organisms and nature. Nonetheless, a relatively low attention is given to their analysis and fate tracking in the environment. In this context, the current paper, embedded in a large study of fate and impact of formulated pesticides in soil, focuses on the analysis of these formulation ingredients. It mainly highlights and discusses the characteristic response of these ingredients in liquid chromatography-mass spectrometry-based untargeted screening of two commercial herbicides applied on soil. This characteristic response is based on different spectral and chromatographic aspects, as their amplified adducts and double-charged ions formation, or their "wavy" chromatographic profiles and the inversion of their elution order following the polymerization degree. These patterns are briefly discussed in order to explain them, and then thanks to their understanding, 12 different series (165 compounds) of formulation ingredients were outlined and discriminated from active substance and soil metabolites. After, high-resolution and tandem mass spectrometry data were investigated for rapid interseries and intraseries identification-by-chain. In addition, recommendations for methods development and hints on postanalytical data processing for identity determination of these ingredients are given in order to help in enhancing future studies. Limitations of the applied approach are also outlined, and some innovate suggestions are provided based on the described findings.