Abstract
Analysis of ergot alkaloids remains a topic of importance and the European Food Safety Authority (EFSA) has encouraged laboratories to provide monitoring data for the further evaluation of their occurrence in food and feed. While LC-MS/MS has dominated developments in recent years, LC-FLD is still more widespread, especially in developing countries. To improve the analysis of ergot alkaloids by LC-FLD, we developed an improved protocol introducing lysergic acid diethylamide (LSD) for internal standardization. Several aspects such as the composition and pH of the extraction medium, type of sorbent and conditions applied for solid-phase extraction/clean-up, use of a keeper during final evaporation and the type of syringe filter used for filtration prior to injection were thoroughly investigated. Optimized conditions comprise extraction by ethyl acetate, methanol and 28% aqueous ammonia in combination with basic aluminum oxide for extract clean-up. Use of a keeper was found inappropriate as LC-FLD analysis was significantly affected by co-eluting keeper components. Similar observations were made with some of the investigated syringe filters, where polytetrafluoroethylene (PTFE) proved to be the most suitable. Validation and application of the optimized methodology to real samples provided limits of detection and quantification suitable for the evaluation of relevant ergot alkaloid contaminations in rye and bakery products with superior precision that was facilitated by the introduced internal standard, LSD.
Highlights
Flour and bakery products are well known for their possible contamination by ergot alkaloids, because of the prominent sclerotia formed by Claviceps purpurea when it grows on rye
Toxins 2019, 11, 184 ergot alkaloids has been identified, which has been the subject of a detailed evaluation by the European Food Safety Authority (EFSA) [2]
With the objective to establish a straightforward and reliable LC-FLD method for the quantification of the 12 representative ergot alkaloids in rye products, a special focus was put on the optimization of reported protocols for sample preparation in addition to the implementation of a suitable internal standard
Summary
Flour and bakery products are well known for their possible contamination by ergot alkaloids, because of the prominent sclerotia formed by Claviceps purpurea when it grows on rye.other cereals such as wheat, barley, millets and oats can be affected, sometimes by different species like Claviceps africana producing a slightly modified ergot alkaloid spectrum [1].From the many alkaloids produced by the genus Claviceps, a representative set of 12 predominantToxins 2019, 11, 184; doi:10.3390/toxins11040184 www.mdpi.com/journal/toxinsToxins 2019, 11, 184 ergot alkaloids (ergometrine, ergotamine, ergosine, ergocornine, ergokryptine, ergocristine and their corresponding inine-epimers) has been identified, which has been the subject of a detailed evaluation by the European Food Safety Authority (EFSA) [2]. Flour and bakery products are well known for their possible contamination by ergot alkaloids, because of the prominent sclerotia formed by Claviceps purpurea when it grows on rye. Other cereals such as wheat, barley, millets and oats can be affected, sometimes by different species like Claviceps africana producing a slightly modified ergot alkaloid spectrum [1]. To monitor human and livestock exposure and to support minimization strategies for crop production, ergot alkaloids are subject to routine analysis throughout Europe [4]. High recoveries are usually achieved when using a two-phasic extraction mixture of ethyl acetate, methanol and aqueous ammonia followed by filtration through basic alumina [9]
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