title: One-step enzyme immunochromatographic assay for theophylline.
abstract: The convenience of the previously described enzyme immunochromatography method for visually quantifying theophylline in whole blood has been improved with the development of a one-step protocol. The capillary migration and color generation in the two-step enzyme immunochromatographic assay have been combined into a single step. Ascorbic acid is used as a signal inhibitor to delay enzymatic color product formation until the inhibitor itself is consumed. The concept of internal delay reaction is presented and the mechanism of ascorbate's action as an inhibitor to temporarily delay color generation is described. The internal delay reaction has been applied to a practical one-step quantitative visual enzyme immunochromatographic assay for theophylline in whole blood.
authors.affiliation: Syntex Medical Diagnostics, Palo Alto, California 94304.
authors.forename: T M
authors.initials: TM
authors.lastname: Li
authors.forename: R
authors.initials: R
authors.lastname: Chen
authors.forename: S
authors.initials: S
authors.lastname: Leeder
authors.forename: S N
authors.initials: SN
authors.lastname: Stiso
authors.forename: N C
authors.initials: NC
authors.lastname: Sizto
authors.forename: R F
authors.initials: RF
authors.lastname: Zuk
authors.forename: D J
authors.initials: DJ
authors.lastname: Litman
mesh_terms: D001205:Ascorbic Acid; D005949:Glucose Oxidase; D006735:Horseradish Peroxidase; D006801:Humans; D006861:Hydrogen Peroxide; D007124:Immunoenzyme Techniques; D013806:Theophylline / Q000032:analysis* / Q000493:pharmacokinetics
chemical_list: D006861:Hydrogen Peroxide; D013806:Theophylline; D005949:Glucose Oxidase; D006735:Horseradish Peroxidase; D001205:Ascorbic Acid