title: Fluorescence polarization immunoassays for the quantification of caffeine in beverages.
abstract: Homogeneous fluorescence polarization immunoassays (FPIAs) were developed and compared for the determination of caffeine in beverages and cosmetics. FPIAs were performed in cuvettes in a spectrometer for kinetic FP measurements as well as in microtiter plates (MTPs) on a multimode reader. Both FPIAs showed measurement ranges in the μg/L range and were performed within 2 and 20 min, respectively. For the application on real samples, high coefficients of variations (CVs) were observed for the performance in MTPs; the CVs for FPIAs in cuvettes were below 4%. The correlations between this method and reference methods were satisfying. The sensitivity was sufficient for all tested samples including decaffeinated coffee without preconcentration steps. The FPIA in cuvettes allows a fast, precise, and automated quantitative analysis of caffeine in consumer products, whereas FPIAs in MTPs are suitable for semiquantitative high-throughput screenings. Moreover, specific quality criteria for heterogeneous assays were applied to homogeneous immunoassays.
authors.affiliation: BAM Federal Institute for Materials Research and Testing , Richard-Willstätter-Straße 11, 12489 Berlin, Germany.
authors.forename: Lidia
authors.initials: L
authors.lastname: Oberleitner
authors.forename: Julia
authors.initials: J
authors.lastname: Grandke
authors.forename: Frank
authors.initials: F
authors.lastname: Mallwitz
authors.forename: Ute
authors.initials: U
authors.lastname: Resch-Genger
authors.forename: Leif-Alexander
authors.initials: LA
authors.lastname: Garbe
authors.forename: Rudolf J
authors.initials: RJ
authors.lastname: Schneider
mesh_terms: D001628:Beverages / Q000032:analysis*; D002110:Caffeine / Q000032:analysis*; D003358:Cosmetics / Q000032:analysis; D016231:Fluorescence Polarization Immunoassay / Q000379:methods*
chemical_list: D003358:Cosmetics; D002110:Caffeine