Evolution through time of Pyrrolizidine Alkaloids detection and quantification

Abstract

Pyrrolizidine Alkaloids (PAs) are a group of naturally occurring alkaloids that are produced by plants as a defense mechanism against insect herbivores. The analytical methodologies employed for their detection have come a long way since the first analytical experiment and in the last 30 years had an enormous development, both technological and experimental. It is notorious that before the generalization of certain technologies, especially in a post-war atmosphere, most scientific researches relied on what it is today thin-layer chromatography. Nevertheless this technique was not sufficient for accurately measure quantities and unambiguously identify compounds, therefore spectroscopic techniques arose as well as chromatographic techniques. While the first never really coped with PAs analysis requirements the latter, either as gas or liquid chromatography allowed the analysis of complex sample matrices. Simultaneously, nuclear magnetic resonance also suffered significant developments while mass spectrometry has become an attractive technique due to increasingly higher maximum resolutions. The observed tendency in recent years, in pyrrolizidine detection and quantification, as well as in many other areas, is that hyphenated techniques are the chosen methods. A large number of papers report multihyphenated methodologies, and the overwhelming majority relies on gas or liquid chromatography.