Monitoring of four dipyrone metabolites in communal wastewater by solid phase extraction liquid chromatography electrospray ionization quadrupole time-of-flight mass spectrometry.

Liquid chromatography quadrupole time-of-flight spectrometry (LC-Q-TOF-MS), equipped with electrospray ionization (ESI), was developed for the determination of the main metabolites of dipyrone - 4-aminoantipyrine (4-AA), 4-acetylaminoantipyrine (4-AAA), 4-formylaminoantipyrine (4-FAA) and 4-methylaminoantipyrine (4-MAA) in communal wastewater after reversed-phase solid phase extraction (SPE) in the low to several μg/l concentration range. Samples originated from conventional wastewater treatment plant (WWTP) using activated sewage sludge as well as from a pilot-scale WWTP operating in mixed mode (activated sewage sludge and cascade biofilms reactors with biofilms growing on fix beds and roots of greenhouse plants). Results of the present study confirmed the outcomes of our previous report according to which, 4-FAA was the most persistent metabolite, while 4-AAA and 4-MAA could be determined in the highest and lowest concentration, respectively.