ESR2 Xiaomeng Liang
Project: Identification of plant produced natural toxins leaching from soil
Principal supervisor: Prof. Jan H. Christensen
Intro to project:
Toxins released from plants to aqueous environment are considered as an important natural source of water contamination and may lead to many health problems. The majority of these toxins and their transformation products, however, are unidentified. In the project, a state-of-the art non-target screening approach is proposed in order to determine the presence of these toxins in soil leachate and correlate them to the natural origin. Compared to traditional target screening, with this new method, all substances in the sample will be analyzed without any pre-selection, giving an unbiased dataset with both known and unknown compounds included.
The project started in Jun 2017 with initial focus on two classes of natural compounds: 1) steroids, 2) naphthalene and anthracene analogs. A suspect list of candidate structures and their predicted physiochemical properties (eg. log Kow, Chromatographic Hydrophobicity Index -- CHI) was generated while the list remains expanding.
A small sampling campaign was carried in Aug 2017, three different plants species (Convallaria, Nerium, Gossypium) and their top soils were collected from Horticultural Gardens, University of Copenhagen.
A preliminary analysis of a few representative toxins was conducted to help establish the nontarget screening platform. Metabolites from the obtained specimen were extracted and screened via UPLC-qTOF and compared with commercial standards as an evaluation of the matrix effect. Different eluent effects (buffer pH, additives, organic modifiers) and ionization behaviours in both positve and negative modes were evaluated both in solvent and in specimens for method optimization.
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