If one wants to find minerals in the form they are mobilised in the plant

If one wants to find minerals in the form they are mobilised in the plant, how will the analysis of
the exudate help?

An analysis of the xylem exudates shows that though some of the nitrogen travels as inorganic ions, much of it is carried in the organic form as amino acids and related compounds. Similarly, small amount of phosphorus and sulphur are carried as organic compunds. In addition, small amount of exchange of materials does take place between xylem and phloem.