title: Evaluation of the anthropogenic input of caffeine in surface waters of the north and center of Portugal by ELISA.
abstract: This study comprises the development of an enzyme-linked immunosorbent assay (ELISA) for the quantification of caffeine in complex aqueous matrices without any sample clean-up procedure. Salinity and dissolved organic matter were selected as potential interfering agents. The addition of a sample buffer containing bovine serum albumin (BSA) prior to the sample was found to decrease the influence of those interfering agents. The working range of the developed method was 0.1-100 μg L(-1). Quantification of caffeine was possible in 43 out of 51 real aqueous samples, at values between <LOD and 15 μg L(-1). Results correlate well with those obtained by LC-MS/MS. To the best of our knowledge this is the first study dealing with the quantification of caffeine in Portugal's surface waters.
authors.affiliation: CESAM & Department of Chemistry, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal.
authors.forename: Carla Patrícia
authors.initials: CP
authors.lastname: Silva
authors.affiliation: CESAM & Department of Chemistry, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal; Department of Complementary Sciences, Superior School of Health Technology of Coimbra, Rua 5 de Outubro, S. Martinho do Bispo, Apartado 7006, 3040-854 Coimbra, Portugal.
authors.forename: Diana L D
authors.initials: DL
authors.lastname: Lima
authors.affiliation: BAM Federal Institute for Materials Research and Testing, Department of Analytical Chemistry, Reference Materials, Richard-Willstaetter-Str. 11, D-12489 Berlin, Germany.
authors.forename: Rudolf J
authors.initials: RJ
authors.lastname: Schneider
authors.affiliation: CESAM & Department of Chemistry, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal; Department of Applied Chemistry and Physics, University of León, Campus de Vegazana, 24071 León, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Otero
authors.affiliation: CESAM & Department of Chemistry, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal. Electronic address: valdemar@ua.pt.
authors.forename: Valdemar I
authors.initials: VI
authors.lastname: Esteves
mesh_terms: D002110:Caffeine / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D004797:Enzyme-Linked Immunosorbent Assay; D005618:Fresh Water / Q000737:chemistry*; D011174:Portugal; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D002110:Caffeine
keywords: Anthropogenic markers; Caffeine; ELISA; Surface water