TripleQuad MRM-MS detection of 4-MU.
Hydroxyl-chromen-2H-one compounds can be detected in Q1 scan as a (M-H)- ion and, under specific collision energy, the hetero-cycle is broken with a neutral loss of the fragment containing–COO•. We propose that the remaining fragment undergoes a molecular rearrangement to obtain a more stable structure. For enzymatic product detection and quantification, two transitions are monitored: 175/119 (4-MU) and 217/160 (internal standard). A. Collision induced dissociation fragmentation spectrum (MS2) of the analyte (4-MU), obtained using an ABSciex 5500, and MRM-MS transition spectrum monitored during the MPS IV assays (175/119); B. Collision induced dissociation fragmentation spectrum (MS2) of the internal standard (4-propyl-5-hydroxy-7-methyl-2H-chromen-2-one), obtained using an ABSciex 5500, and MRM-MS transition spectrum monitored during the MPS IV assays (217/160).
