A systematic assessment of the variability of matrix effects in LC-MS/MS analysis of ergot alkaloids in cereals and evaluation of method robustness

The study presents for the first time a systematic investigation of matrix effects in the LC-MS/MS analysis of ergot alkaloids in cereals. In order to assure the accuracy of the results, several approaches to minimize/eliminate matrix effects were investigated including variation of ionization techniques, chromatography and sample preparation on different grain types and grain varieties. It was revealed that the use of UPLC and careful choice of sample preparation might reduce signal suppression/enhancement. In general, ergometrine was found to be the most susceptible among the ergot alkaloids studied, but none of the used approaches suggested a total elimination of matrix effects; only less than half of its MS signal could be recovered. The late-eluting compounds were less affected by matrix components in all conditions tested. Further, the robustness of the applied LC-MS method was checked by means of a fractional factorial design. The results indicate that small changes to the sample preparation parameters, namely pH and concentration of extraction buffer, shaking time, drying temperature and extraction volumes, did not significantly (alpha = 0.05) affect the recoveries of ergot alkaloids.