# Semisynthesis of Stable Isotope-Labeled Ergot Alkaloids for HPLC-MS/MS Analysis

## TL;DR

This paper describes a method to create stable isotope-labeled ergot alkaloids to improve the accuracy of food safety testing.

## Contribution

A semisynthetic method to produce all priority isotope-labeled ergot alkaloids for HPLC-MS/MS analysis.

## Key findings

- Isotope-labeled ergot alkaloids were successfully synthesized and validated.
- Chromatographic and mass spectrometric properties of labeled and unlabeled compounds matched perfectly.
- The new standards can enhance accuracy and consistency in ergot alkaloid quantification.

## Abstract

Ergot alkaloids (EAs)
are prevalent food contaminants
affecting
cereals, such as rye, wheat, and barley worldwide. To ensure EU safety
standards, the six most common EAs: ergometrine, ergotamine, ergosine,
ergocornine, ergocristine, and ergocryptine, and their epimers, are
quantified using HPLC-MS/MS, as described in the European Standard
Method EN 17425:2021. However, this can be challenging and time-consuming
in food matrices without appropriate internal standards and highlights
the need for more robust and precise analytical tools to support their
monitoring. The development of isotope-labeled EAs directly addresses
this gap, offering improved accuracy and leading to more consistency
across laboratories and consequently to more consumer safety. Therefore,
we developed a semisynthetic approach, building upon our previous
work where native ergotamine was N
6-demethylated
to norergotamine and subsequently remethylated using iodomethane (13CD3-I). Herein, we are now able to present the
successful synthesis of all of the isotopically labeled priority EAs.
These isotope-labeled standards were tested against their native counterparts
using HPLC coupled with HR-MS/MS. The chromatographic and mass spectrometric
properties of the unlabeled and isotopically labeled EAs match exactly,
confirming their successful synthesis and structure. These standards
can now be utilized to enhance the accuracy and reliability of EA
quantification in food and feed.