title: Magnetic solid phase extraction followed by high-performance liquid chromatography for the determination of sulphonamides in milk samples.
abstract: A simple and effective method based on magnetic solid-phase extraction combined with high performance liquid chromatography was used for the determination of nine sulphonamides in milk samples. The extraction and cleanup via silica-based magnetic adsorbent dispersion in milk samples followed by the magnetic isolation and desorption of the analytes using NaOH-methanol. Three different magnetic phenyl silica adsorbents were synthesized by varying the molar ratio of phenyltrimethylsilane and tetramethylorthosilicate; these adsorbents were evaluated for sulphonamides retention in terms of their pH and degree of hydrophobicity. The optimal conditions were a pH of 6.0 and a magnetic:sorbent ratio of 2:1. Under optimal conditions, limits of detection ranging from 7 to 14 μg L(-1) were obtained. The method was validated according with the European Commision Decision 2002/657/EC. The proposed method was applied to analyse sulphonamides in 27 milk samples of different brands. Thirteen samples tested were positive for the presence of sulphonamides.
authors.affiliation: Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Hidalgo, Carr. Pachuca-Tulancingo Km. 4.5, 42076 Pachuca, Hgo, Mexico.
authors.forename: Israel S
authors.initials: IS
authors.lastname: Ibarra
authors.affiliation: Dpto. Química Analítica, Nutrición y Bromatología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Pabellón 4 planta baja, Campus Universitario s/n, 27002 Lugo, Spain. Electronic address: josemanuel.miranda@usc.es.
authors.forename: Jose M
authors.initials: JM
authors.lastname: Miranda
authors.affiliation: Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Hidalgo, Carr. Pachuca-Tulancingo Km. 4.5, 42076 Pachuca, Hgo, Mexico.
authors.forename: Jose A
authors.initials: JA
authors.lastname: Rodriguez
authors.affiliation: Dpto. Química Analítica, Nutrición y Bromatología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Pabellón 4 planta baja, Campus Universitario s/n, 27002 Lugo, Spain.
authors.forename: Carolina
authors.initials: C
authors.lastname: Nebot
authors.affiliation: Dpto. Química Analítica, Nutrición y Bromatología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Pabellón 4 planta baja, Campus Universitario s/n, 27002 Lugo, Spain. Electronic address: alberto.cepeda@usc.es.
authors.forename: Alberto
authors.initials: A
authors.lastname: Cepeda
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D060328:Magnetic Phenomena; D008892:Milk / Q000737:chemistry*; D052616:Solid Phase Extraction / Q000379:methods*; D013449:Sulfonamides / Q000032:analysis / Q000737:chemistry*
chemical_list: D013449:Sulfonamides
keywords: High performance liquid chromatography; Magnetic solid phase extraction; Milk; Phenyl silica adsorbent; Sulphonamides