We measured the passive transport of 10 mM Cbz-D, 100 mM EDC, and 100 mM EDU from the sender to the receiver in three Utube setups. Using 1 H-NMR spectroscopy, we measured the amount of Cbz-D, EDC, and urea waste (EDU) in the sender and receiver after 48 hours (Fig. ). We found that only 0.3% ± 0.01% of Cbz-D, 5% ± 1.2% EDC, and 0.6% ± 0.03% EDU passively diffused from the sender to the receiver within two days (Fig. , Fig. ). Around 1.4% ± 0.03% of Cbz-D, 0% ± 0.01% of EDC and 0.9% ± 0.03% of EDU resided in the chloroform phase. In conclusion, some passive transport takes place, albeit extremely slowly.