title: Assessment of benzophenone-4 reactivity with free chlorine by liquid chromatography quadrupole time-of-flight mass spectrometry.
abstract: The stability of the UV filter benzophenone-4 (BP-4) in free chlorine-containing water was investigated, for the first time, by liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QqTOF-MS). High mass accuracy and resolution capabilities of this hybrid mass spectrometer were used for the reliable assignation of empirical formulae and chemical structures of BP-4 derivatives. Time-course profiles of the parent compound and its by-products were simultaneously recorded by direct injection of sample aliquots, after quenching the excess of chlorine, in the LC-QqTOF-MS system. At neutral pHs, in excess of chlorine, BP-4 showed a limited stability fitting a pseudo-first-order degradation kinetics. A noticeable reduction in the half-lives of BP-4 was observed when increasing the sample pH between 6 and 8 units and also in presence of bromide traces. The reaction pathway of this UV filter involved a first electrophilic substitution of hydrogen per chlorine (or bromide) in the phenolic ring, followed by oxidation of the carbonyl moiety to an ester group, which induced a further electrophilic substitution in the same aromatic ring. Above reactions were also noticed when mixing a BP-4 containing personal care product with chlorinated tap water and in chlorinated swimming pool and sewage water, previously spiked with a BP-4 standard.
authors.affiliation: Departamento de Química Analítica, Nutrición y Bromatología, Instituto de Investigación y Análisis Alimentario (IIAA), Universidad de Santiago de Compostela, Santiago de Compostela 15782, Spain.
authors.forename: N
authors.initials: N
authors.lastname: Negreira
authors.forename: I
authors.initials: I
authors.lastname: Rodríguez
authors.forename: R
authors.initials: R
authors.lastname: Rodil
authors.forename: R
authors.initials: R
authors.lastname: Cela
mesh_terms: D001577:Benzophenones / Q000737:chemistry*; D002623:Chemistry Techniques, Analytical; D002713:Chlorine / Q000737:chemistry*; D002853:Chromatography, Liquid; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry
chemical_list: D001577:Benzophenones; C009361:sulisobenzone; D002713:Chlorine