To quantify the polarization level we compare a C spectrum of a hyperpolarized sample that underwent the purification procedure, and a thermal equilibrium C spectrum of a 500 mM [1- C]fumarate sample (isotopically enriched). Both spectra were acquired using a 𝜋/2 pulse and the results are shown in Fig. . From this comparison, and knowing the concentrations of fumarate in the purified and control samples, we are able to calculate that the polarization of the hyperpolarized fumarate molecules (63 mM) in the purified sample was 25%. The total fumarate concentration in the purified sample was 354 mM, due to the addition of unpolarized fumarate molecules to aid in fast precipitation. The addition of unpolarized fumarate is not necessary for the purification step, but speeds up the rate of precipitation which is convenient for this preliminary demonstration.