Figure 4

Typical mass spectra obtained in MALDI-TOF MS of (a) the reagent blank and (b) the paraben derivatives under optimal derivatization conditions. The [M + H]+ of signals 1, 2, 3, 4, and 5 are Dansyl-MP, Dansyl-EP, Dansyl-EP-d5 (IS), Dansyl-PP and Dansyl-BP at m/z 386.2, 400.2, 405.2, 414.2 and 428.2, respectively.