An easy method for preparing radioactive methyl esters of eicosanoids suitable as ligands in radioimmunoassays

A rapid and convenient method is described for methylating prostanoids and other arachidonic acid metabolites. With 3H-methyl iodide of high specific activity, tracers for radioimmunoassay can be produced at a cost which is only a fraction of that of labeled compounds currently available. In radioimmunoassays for PGE2, TXB2 and 6-keto-PGF1 alpha, labeled methyl esters gave results which were comparable to those obtained with the use of tritiated free acids as radioligands.