title: Aqueous chlorination of acebutolol: kinetics, transformation by-products, and mechanism.
abstract: This study investigated the reaction kinetics and the transformation by-products of acebutolol during aqueous chlorination. Acebutolol is one of the commonly used β-blockers for the treatment of cardiovascular diseases. It has been frequently detected in the aquatic environment. In the kinetics study, the second-order rate constant for the reaction between acebutolol and chlorine (k app) was determined at 25 ± 0.1 °C. The degradation of acebutolol by free available chlorine was highly pH dependence. When the pH increased from 6 to 8, it was found that the k app for the reaction between acebutolol and free available chlorine was increased from 1.68 to 11.2 M(-1) min(-1). By comparing with the reported k app values, the reactivity of acebutolol toward free available chlorine was found to be higher than atenolol and metoprolol but lower than nadolol and propranolol. Characterization of the transformation by-products formed during the chlorination of acebutolol was carried out using liquid chromatography-quadrupole time-of-flight high-resolution mass spectrometry. Seven major transformation by-products were identified. These transformation by-products were mainly formed through dealkylation, hydroxylation, chlorination, and oxidation reactions.
authors.affiliation: Environmental Research Group, Department of Chemistry, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia.
authors.forename: Wan Nor Adira Wan
authors.initials: WN
authors.lastname: Khalit
authors.affiliation: Environmental Research Group, Department of Chemistry, Faculty of Science, University of Malaya, 50603, Kuala Lumpur, Malaysia. khengsoo@um.edu.my.
authors.forename: Kheng Soo
authors.initials: KS
authors.lastname: Tay
mesh_terms: D000070:Acebutolol / Q000737:chemistry*; D058671:Adrenergic beta-1 Receptor Antagonists / Q000737:chemistry*; D000319:Adrenergic beta-Antagonists / Q000737:chemistry; D000959:Antihypertensive Agents / Q000737:chemistry*; D001262:Atenolol / Q000737:chemistry; D002713:Chlorine / Q000737:chemistry; D002853:Chromatography, Liquid; D054879:Halogenation; D007700:Kinetics; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D011433:Propranolol / Q000737:chemistry; D014867:Water / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification
chemical_list: D058671:Adrenergic beta-1 Receptor Antagonists; D000319:Adrenergic beta-Antagonists; D000959:Antihypertensive Agents; D014874:Water Pollutants, Chemical; D014867:Water; D002713:Chlorine; D001262:Atenolol; D000070:Acebutolol; D011433:Propranolol
keywords: Beta-blockers; Chlorination; Degradation by-products; Pharmaceuticals; QTOF; Water treatment