University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Email: schalk@unf.edu
Website: @unf

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Fluorescence

Classification: Fluorescence -> polarized

Citations 2

"Direct Stopped-flow Fluorescence Polarization Immunoassay Of Abused Drugs And Their Metabolites In Urine"
Clin. Chem. 1994 Volume 40, Issue 8 Pages 1489-1493

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Dolores Perez-Bendito, Augustina Gomez-Hens and Abaji Gaikwad

Abstract: Two solution were prepared for filling the two drive syringes of the stopped-flow module. One contained 10 µL of urine and an appropriate volume of the fluorescein-labelled analyte in buffer in a final volume of 0.5 mL. The other contained an appropriate volume of the antibody in 0.5 mL of buffer. Portions (40 µL) of the two solution were transferred to the mixing chamber at 20 ml/s. The time course of the fluorescence intensity was measured in the two emission channels at 550 nm (excitation at 494 nm). The stopped-flow module was computer-controlled and the initial reaction rate was determined in 5-10 s. The procedure was exemplified by the determination of amphetamine and of the metabolites benzoylecgonine and 11-nor-Δ8-tetrahydrocannabinol-9-carboxylic acid. Calibration graphs for these three were 20-300, 15-300 and 10^-400 µg/l respectively, with detection limits of 7, 5 and 3 µL/l, 3-12 times lower than by conventional fluorescence polarization immunoassay. The new method was also more precise (RSD of 1.4-3.6%, vs. 2.2-7.4%) and recovery was close to 100%. The correlation between the two methods was excellent (r > 0.99).
Drugs Amphetamine Benzoylecgonine Urine Stopped-flow Computer Method comparison

"Comparison Of Digoxin Analysis By High Performance Liquid Chromatography - Post-column Derivatization And Fluorescence-polarization Immunoassay"
Xenobiotica 1990 Volume 20, Issue 6 Pages 635-643

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L. Embree and K. M. McErlane

Abstract: The method described previously (J. Chromatogr., 1989, 496, 321) was compared with the Abbott TDx method. The r value between the two methods for digoxin added to drug-free serum was 0.9897 (n = 7). However, serum from digitalized patients showed higher digoxin levels by the TDx method, probably owing to cross-reactivity of metabolites. Cross-reactivity of the TDx method towards endogenous material in the serum of certain patient groups was an even greater problem. The HPLC method (loc. cit.) gave complete resolution of digoxin. The calibration graph for this method was rectilinear for 0.5 to 3.3 ng mL-1 of digoxin in a 3 mL serum sample, with a mean coefficient of variation of 5.6% and a detection limit of 0.5 ng injected.
Digoxin Serum Human Post-column derivatization Calibration Detection limit