Ergot alkaloids: Quantitation and recognition challenges

摘要

Bread, flour, infant formula and baby food samples (n=109, from which n=54 made of or containing rye), collected in 2001, 2003, and 2005, were analysed for ergot alkaloids. Samples were extracted using acidic conditions and the extracts subjected to an automated solid-phase clean up using combined cation exchange/reversed-phase sorbent cartridges (Oasis-MCX). Subsequent chromatographic separation and analysis was performed by liquid chromatography (LC) with fluorescence detection (FLD) and by LC with mass spectrometric detection (MS/MS). The ergot alkaloid (EAs) content of a sample was defined as the sum of the 16 alkaloids ergometrin(in)e, ergosin(in)e, ergotamin(in)e, ergostin(in)e, ergocornin(in)e, α-ergocryptin(in)e, β-ergocryptin(in)e and ergocristin(in)e. Comparability of results obtained by LC-FLD and LC-MS/MS was satisfactory, but varied for different alkaloids. The use of dihydro-ergocristine as an internal standard considerably improved the reliability of analytical data from LC-MS/MS. Compared with earlier data (Baumannet al., 1985) for median levels of ergot alkaloids in rye flour (140 ng/g) and bread (21.3 ng/g) from Switzerland, the median values for ergot alkaloids in rye flour collected in 2001 (n=13) and in 2005 (n=2) were 172 ng/g and 160 ng/g, respectively. The median values for bread (fresh weight) collected in 2001 (n=14), 2003 (n=7), and 2005 (n=2) were 87 ng/g, 120 ng/g, and 156 ng/g, respectively. Low levels of ergot alkaloids were also found in wheat products and in some infant formulae and baby foods containing rye. By additional LC-MS/MS experiments, the possible natural occurrence of ergot congeners containing the 9,10-unsaturated ergoline cation (m/z=223) was investigated. In a few samples, ergovalin(in)e was tentatively identified by these means.