A time-resolved fluoroimmunoassay for the determination of prostaglandin F2 alpha

We describe a solid-phase immunoassay based on fluorescence detection for Prostaglandin F2 alpha (PGF2 alpha). Europium was used as the fluorescence marker. Prostaglandin F2 alpha was covalently bound to poly-L-lysine (PL) and labelled by coupling Eu3+ via the complexonate diethylenetriaminepentaacetic acid (DTPA). The labelled PGF2 alpha was tested in a competitive immunoassay. The detection limit for PGF2 alpha was about 2.2 pg per microtiter well. The intraassay-variation was 17.2% at 1.1 pg, 4.1% at 10 pg and 7.6% at 90 pg. The precision was determined by measuring various amounts of unlabelled PGF2 alpha (2.5 to 2,400 pg) in the assay buffer. The regression line for these studies resulted in a good correlation (y = 1.01x +/- 0.03; r = 0.996; n = 21). The results of a radioimmunoassay and of the fluoroimmunoassay were similar (y = 0.983 +/- 0.04; r = 0.988; n = 15). The new method enables PGF2 alpha analyses at concentrations in the fmolar range.