Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry is a powerful tool for polymer characterization. It has been used to understand the enzymatic polymerization of 4-phenylphenol and to monitor number average molecular weight and weight average molecular weight of the polymer as a function of systematic addition of hydrogen peroxide (H(2)O(2)) in the reaction. A novel method, an introduction of internal standard for quantification of data, has been developed for MALDI-TOF MS to investigate the fate of each mers during the reaction. The preliminary data suggest that this approach provides new insight on the enzymatic synthesis, which is not available by other techniques. For the first time, we are able to understand the fate of several mers as a function of reaction conditions. The relative content of each mer increases with the addition of H(2)O(2), except for dimer and trimer. For example, the concentration of dimer species decreases as a function of H(2)O(2). On the other hand, the concentration of trimer species increases first and then decreases in the course of the reaction.