The R2 values obtained by fitting a second order polynomial model were above 0.88 and the Q2 values above 0.6 except for ergosine (Q2 = 0.49), ergotamine (Q2 = 0.57), ergokryptine (Q2 = 0.53) and ergokryptinine (Q2 = 0.57). The results ( Supplemental Fig. S4) indicated that, in the range investigated (pH 7–pH 10), an increase of the extraction solvent buffer pH has a positive effect on the extraction efficiency of all analytes.