Fig. 3
Differentiation of isotopic SPLs by accurate MS together with complete separation. Cer (d18:1/24:1) (tR = 17.219 min) yields precursor ions at m/z 648.6280 and m/z 650.6343, the latter one is the [M + 2] isotopic ion which will interfere with the precursor ion of Cer (d18:1/24:0) (tR = 18.566 min) at m/z 650.6436. The mass differentiation cannot be distinguished by QQQ. If the two peaks cannot be completely separated by LC, the quantification result of Cer (d18:1/24:0) will be artificially high