Abstract: The invention concerns a chromatographic measurement. The aim of the invention is to measure at least one of the elements chosen from among Pu (IV), Pu (VI), uranium and nitrates, present in a solution by liquid phase chromatography. This aim is attained by a process comprising the following stages:a) injection of a sample of the solution on a stationary phase comprising an apolar-type support,b) elution by a mobile liquid phase which comprises a counter-ion of ammonium type, sulfate ion, an acid of a normality equal to or greater than 0.001 N, a mixture of solvents comprising an alcohol in C.sub.1 -C.sub.4, a polar modifying organic solvent different from an alcohol, miscible with water, and water, in order to obtain an eluate, andc) analysis of the eluate so as to determine the element(s) present.