title: Development of an enzyme-linked immunosorbent assay for caffeine.
abstract: A competitive enzyme-linked immunosorbent assay suitable for the measurement of caffeine in plasma and serum has been developed. Sheep immunised with an immunogen prepared by coupling 7-(5-carboxypentyl)1,3-dimethylxanthine to egg albumin produced antibodies with little crossreactivity with the metabolites of caffeine. The enzyme label was prepared by coupling 7-(5-carboxypentyl)-1,3-dimethylxanthine to peroxidase using the mixed anhydride method. The assay, which has a sensitivity of 0.01 mumol/l, permits direct measurement of caffeine in plasma and serum samples. 50 plasma samples measured by ELISA and by an established radioimmunoassay showed a correlation of r = 0.97 (P less than 0.001).
authors.affiliation: Department of Biochemistry, University of Surrey, Guildford, U.K.
authors.forename: S A
authors.initials: SA
authors.lastname: Fickling
authors.forename: S M
authors.initials: SM
authors.lastname: Hampton
authors.forename: D
authors.initials: D
authors.lastname: Teale
authors.forename: B A
authors.initials: BA
authors.lastname: Middleton
authors.forename: V
authors.initials: V
authors.lastname: Marks
mesh_terms: D002110:Caffeine / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D011863:Radioimmunoassay; D015203:Reproducibility of Results
chemical_list: D002110:Caffeine