Determination of 2,3-dinor-6-ketoprostaglandin F1 alpha in urine samples by liquid chromatography and radioimmunoassay

A method for 2,3-dinor-6-ketoprostaglandin F1 alpha quantification based on high-performance liquid chromatography-radioimmunoassay is described. Samples are acidified to pH 3 and processed through C18 disposable cartridges. The prostanoids are eluted with methyl formate and further separated on a reversed-phase column using acetonitrile-acetic acid-triethylamine buffer (32:68). Studies of the effect of eluent pH were performed in order to optimize resolution and separation of 2,3-dinor-6-keto-PGF1 alpha from other prostanoids. Eluates were collected and assayed by radioimmunoassay using a heterologous system, with 6-keto-PGF1 alpha as radioligand and an antiserum with high cross-reactivity for 2,3-dinor-6-keto-PGF1 alpha. Sensitivity, precision and accuracy of the assay procedure are reported together with the validation of its specificity. The proposed method has been applied to the determination of this prostacyclin metabolite in human urine.