Comparison of radioimmunoassay and high-resolution gas chromatography mass spectrometry for the quantitative determination of serum thromboxane B2 and 6-keto-PGF1 alpha after pharmacological blockade of thromboxane synthetase.

Radioimmunoassay (RIA) and high-resolution gas chromatography-mass spectrometry (HRGC-MS) were compared for the determination of serum 6-keto-PGF-1 alpha and TXB2 in a situation of drug-altered arachidonate metabolism. Results were comparable for TXB2 in both conditions. 6-keto-PGF1 alpha RIA determinations (with two different antisera) revealed increased levels in dazoxiben-treated samples, which were not confirmed by HRGC-MS. The assay were repeatedly checked in controlled conditions to investigate these discrepancies. Interference was found with both antisera, due to the drug-induced change in metabolism.