- Fast 4.5-min pyrrolizidine alkaloids analysis separates most compounds to baseline.
- Simple mobile phase and gradient elutes compounds quickly with excellent peak shape.
- Robust Raptor ARC-18 column outlasts traditional C18 columns under acidic conditions.
Pyrrolizidine alkaloids (PAs) are toxins found naturally in a wide variety of plant species (e.g., daisies, forget-me-nots, and legumes, among others). They are secondary metabolites formed to protect plants against herbivores and, according to the European Food Safety Authority (EFSA), are likely the most widely distributed natural toxins. While there are over 6000 plant species known to contain pyrrolizidine alkaloids, only a few species have been involved in the direct poisoning of people or animals. And, of the roughly 700 known PAs, the 1,2-unsaturated compounds have been identified as the most toxic, capable of causing fatal liver damage. Herbs, teas, honey, and cereal may be contaminated with pyrrolizidine alkaloids if plants containing PAs are accidentally co-harvested or used as a food source for bees.
Because of the World Health Organization's (WHO) Codex Alimentarius Commission adoption of the “as low as reasonably achievable” (ALARA) principle for PAs—along with many regional efforts to monitor these toxic compounds in food, feed, and medicines, the need for fast, accurate pyrrolizidine alkaloids analysis methods is on the rise. At present, the only harmonized method was developed and validated by the German Federal Institute for Risk Assessment (BfR) [1]. It employs a sulfuric acid digestion, an SPE C18 cleanup, and analysis via LC-MS/MS. The example method provided in the BfR protocol uses a 150 x 2.1 mm, 1.9 µm fully porous particle C18 column and produces a run time of 15 minutes with the last compound, lasiocarpine-N-oxide (LaN), eluting at 9.33 minutes. However, in the case study presented below, switching to a superficially porous 50 x 2.1 mm, 2.7 µm Raptor ARC-18 column provides sufficient retention while still eluting LaN in just 3.2 minutes (4.5 minute total run time). Note that although a UHPLC instrument was used in this example, it is not necessary for this analysis. Excellent peak shapes were obtained and all compounds, except for echimidine and its corresponding N-oxide, were separated to baseline. The Raptor ARC-18 column’s unique phase chemistry also results in longer lifetimes under acidic conditions compared to traditional C18 columns.
As the scope of pyrrolizidine alkaloids analysis continues to expand, methods will have to grow along with it, but for today’s challenges, using a Raptor ARC-18 column allows labs to optimize method conditions, shorten the overall run time, and increase sample throughput.
References
- Bundesinstitut für Risikobewertung (BfR), BfR-PA-Tee-2.0/2014, Bestimmung von Pyrrolizidinalkaloiden (PA) in Pflanzenmaterial mittels SPE-LC-MS/MS, 2014. https://www.bfr.bund.de/cm/343/bestimmung-von-pyrrolizidinalkaloiden.pdf
