I tried neutralizing orthophosphoric acid with triethylamine using 1:3 stoichiometry by stirring the two liquids at room temperature but a lot of triethylamine remains unreacted which suggests incomplete reaction. When I added excess of triethylamine, I got a viscous, colourless and dense oil which settled at the bottom after a day of stirring. How can I characterize the oily compound ? I want the tris-(triethylammonium) phosphate and want to make sure bis-(triethylammonium) hydrogen phosphates and triethylammonium dihydrogen phosphates are absent. I could not find any literature to compare my 31P NMR data with. HRMS either gives the mass of the cation (+ve mode) or the anions (negative mode) and does not help me differentiate between the three possible salts. Any help to get relevant literature or to select appropriate characterization technique will be immensely appreciated.

I also tried to use Ion exchange chromatography and exchange the potassium ion with triethylammoonium ion in K3PO4 and obtained a semi crystalline mass. But I still want to characterize the compound and I have no prior experience in characterizing such salts.