The ion suppression phenomenon in liquid chromatography-mass spectrometry and its consequences in the field of residue analysis

During their first period of development, the liquid chromatography-mass spectrometry techniques were met with great enthusiasm from most end-users. An extended application range, the needlessness of derivatisation step prior to injection, the possibility of reduced sample preparation and high throughput analysis were some of the arguments given in favor of these techniques. Few years and more than thousands applications later, more attention is paid to their adverse aspects and limitations, especially regarding the existence of matrix effects. Such problems are well known for many years and may concern various detection techniques. But ion suppression appears as a kind of matrix effect specifically linked to mass spectrometry that probably represents one of the main source of pitfalls in liquid chromatography-mass spectrometry (LC-MSn). In the actual tendency to promote these techniques for control purposes in the field of residue analysis, it was thought necessary to highlight one of their possible side-effect which may have critical consequences for the analytical results. In this context, the objectives of the present article, which is based on a literature review and additional experiments, were to present the origins and mechanisms of ion suppression, to expose several case studies illustrating its consequences in the field of residue analysis, and finally to propose and comment on some solutions that may overcome this problem.