To quantify how effectively the precipitation/redissolution procedure excluded the catalyst molecules from the solutions, inductively coupled plasmaoptical emission spectrometry (ICP-OES) elemental analysis was performed on a purified sample. The standard procedure was used to purify the fumarate, but with an additional washing step; while on the sinter, the solid fumarate powder was washed twice with deionized water, and twice with acetone to remove residual catalyst solution from the surface of the crystals The catalyst concentration in the final solution was determined by ICP-MS to be 16 µM, which corresponds to a reduction from the initial concentration of more than 99.5%. Thermal equilibrium C NMR spectra were acquired of the control and purified solutions in an 11.7 T magnet. The 1024-scan spectra were acquired with 1 H decoupling, using a pre-scan delay of 30 s and 30° flip angle pulses. The results qualitatively show contamination of the unpurified solution with the acetylene dicarboxylate starting material and unassigned reaction side products, but no contaminants are visible in the purified sample spectrum. From these spectra, we can set an upper bound on the concentration of starting material in the purified solution at 0.6 mM, which corresponds to less than 0.4% of the fumarate concentration. Thermal equilibrium 1 H NMR spectra of the control and purified samples are included in the Supporting Information, which show contaminant molecules at a level of less than 1% compared to the fumarate concentration. Additionally, high-performance liquid chromatography (HPLC) spectra were acquired of the control and purified samples, and this data is included in the Supporting Information.