title: A rate turbidimetric immunoassay for theophylline using biotin-avidin system.
abstract: We describe a biotin-avidin based rate turbidimetric homogeneous immunoassay for the determination of serum theophylline with a measuring range of 0-40 micrograms/ml. The assay features an avidin-biotin-labeled theophylline conjugate and a monoclonal antibody. The rate of change of turbidity caused by the antibody-conjugate complexing was monitored on the Beckman Synchron CX 4 System at 340 nm and 37 degrees C. Theophylline in a sample inhibited the complexation, and the extent of inhibition allowed the quantitation of theophylline in the sample. The within-run coefficient of variation (CV) was < 3.7% and the between-run CV was 5.2-9.2% depending on the theophylline concentration. Linear regression analysis showed a good correlation with an established fluorescence polarization immunoassay (r = 0.9866, n = 94).
authors.affiliation: Beckman Instruments, Brea, California.
authors.forename: C
authors.initials: C
authors.lastname: Oh
authors.forename: J
authors.initials: J
authors.lastname: Kim
authors.forename: B
authors.initials: B
authors.lastname: Kearns
authors.forename: A
authors.initials: A
authors.lastname: Cheng
authors.forename: T
authors.initials: T
authors.lastname: Dobashi
mesh_terms: D001360:Avidin; D001710:Biotin; D005069:Evaluation Studies as Topic; D016231:Fluorescence Polarization Immunoassay; D006801:Humans; D007118:Immunoassay / Q000379:methods* / Q000706:statistics & numerical data; D009391:Nephelometry and Turbidimetry / Q000379:methods* / Q000706:statistics & numerical data; D012680:Sensitivity and Specificity; D013806:Theophylline / Q000097:blood*
chemical_list: D001360:Avidin; D001710:Biotin; D013806:Theophylline