LC-MS tools for environmental and food analysis

Seminar

Title: LC-MS tools for environmental and food analysis

Speaker: Teresa Galceran

Affiliation: University of Barcelona, Spain

Host: Cristina Silva Pereira, Applied and Environmental Mycology Laboratory

Abstract:

The purpose of this presentation is to give an overview of problems found on the analysis by LC-MS of several families of compounds in food and environmental samples that can be solved by taking advantage of the potential of MS instruments. Several aspects such as the ionization technique, the increase in resolution or the use of accurate mass measurements that help in the analysis of the above mentioned compounds will be commented. The use of three different ionization sources, electrospray (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) has been evaluated and some of the results obtained will be shown. Examples of ionization conditions, matrix effects, the role of the dopant in APPI and also the fragmentation behaviour for several compounds will be included.
In LC-MS analysis the resolving power and mass accuracy of the MS analyzer are key aspects. In this context, the advantage of using multiple stage mass spectrometry (MSn) for the establishment of fragmentation pathways and the improvement of selectivity and sensitivity will be commented. Although MS based methods can be considered as highly selective, interferences can occur mainly in the analysis of relatively dirty samples since some compounds can share the same MS characteristics than the analytes. The benefit of increasing resolving power when working in selected ion monitoring (SRM) will be illustrated with examples on the elimination of interferences from sample matrix and on avoiding false negatives/positives. Accurate mass measurements enable determination and confirmation of elemental compositions and characterization of fragments obtained in MSn experiments. Some examples of the correct assignment of product ions obtained in the fragmentation of several compounds and the elucidation of the structure of unknown compounds will be shown.

M Teresa Galceran is Professor of Analytical Chemistry at the University of Barcelona and is the head of a research group that have 10 researchers. She has been the President of the Spanish Chromatographic Society and actually is Vice-president of the Spanish Analytical Chemistry Society. She has co-authored more than 100 peer-reviewed publications.