An inventive substrate is provided which includes a substrate compound of formula A-B1-B2-B3-B4: wherein A is a sugar moiety; B1 is a linker moiety allowing the conjugation of moiety A and the remaining structure of the substrate; B2 is a linker moiety with a free reactive amino group so as to be available for reaction with carboxylic acids or detectable tags; B3 contains a permanently charged element such as a quaternary ammonium group so as to increase sensitivity for mass spectrometry analysis; and B4 of various carbon length conferring specificity amongst individual substrates in detection methods. Also provided is a molecule of the formula B1-B2-B3-B4, with similar structural characteristics to an enzymatic product produced by the action of a target enzyme on an inventive substrate. Further provided are methods for using inventive substrates for detecting enzymatic activity.