Phase-Modulation Fluorescence Lifetime Immunoassay of Dichlorprop

✍ Scribed by F.G. Sanchez; A. Navas; J. Lovillo

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 534 KB
• Volume: 214
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1006/abio.1993.1510

✦ Synopsis

A homogeneous immunofluorimetric technique to determine dichlorprop herbicide is described. Simultaneous determinations of both free and antibody-bound fluoresceinamine-labeled dichlorprop were carried out by measuring phase-resolved fluorescence or modulation-resolved fluorescence. The difference between the recorded values of the fluorescence lifetimes of the two species quantifies selectivity. Multifrequency heterogeneity analyses of free and bound labeled dichlorprop gave 3.68 +/- 0.03 and 4.28 +/- 0.02 ns, respectively. The differences between the phase-angles of the two species (117.5 degrees and 127.2 degrees) correspond to a difference between fluorescence lifetime values of 600 ps. This lifetime difference permits the quantitative determination of the two species simultaneously. The mean relative standard deviation of the set of three calibration curves when fitted to radioimmunoassay (chi 2 5 x 10(-4)) was 6%. The practical dynamic range was 0.1 to 100 micrograms.ml-1. On the other hand, the fractional contributions of both species, free and bound, to the total lifetime measured by demodulation, permit quantitative calculation of the two components. Both methods gave similar analytical specifications.