Crossover of compounds between chambers may affect the reaction efficiency and electrocatalyst lifetime. Glycerol crossover through the BPM was studied to determine the magnitude and rate of permeation over several days. For these experiments, CO2RR in 25 ml of 0.500 M Na2CO3 solution prepared in D2O was paired with GEOR at 10.0 mA cm -2 for 24 hours in a two-electrode configuration. 400 µL aliquots of the catholyte were sampled at 6, 18, and 24 hours during the electrolysis. The solutions remained in the cell without electrolysis for 48 hours after the end of the CP experiment and were sampled at 48 and 72 hours after the start of the experiment. The concentration of glycerol in the Na2CO3 solution was determined using 1 H NMR with a DMSO internal standard for quantification.