Simultaneous GLC determination of clofibrate and clofibric acid in human plasma

A simultaneous assay for the detection of clofibrate and its metabolite, clofibric acid [2-(p-chlorophenoxy)-2-methylpropionic acid], is described. This GLC method is rapid and does not require a derivatization step. It is sensitive to 1-microgram/ml levels of either compound in biological samples and can be used to characterize the in vivo conversion of clofibrate ester to the free acid.