Assessment of benzophenone-4 reactivity with free chlorine by liquid chromatography quadrupole time-of-flight mass spectrometry

► LC-QTOF-MS was used to investigate the reactivity of BP-4 with chlorine. ► In excess of free chlorine, BP-4 degrades following a pseudo-first order rate. ► Water pH and bromide traces affect the half-life of BP-4. ► BP-4 by-products arise from oxidation and halogenation processes.