Development of an enzyme-linked immunosorbent assay for caffeine.
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).
Fickling
S A
SA
Department of Biochemistry, University of Surrey, Guildford, U.K.
Hampton
S M
SM
Teale
D
D
Middleton
B A
BA
Marks
V
V
D002110:Caffeine / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D011863:Radioimmunoassay; D015203:Reproducibility of Results
D002110:Caffeine