The internal standard stock solution was prepared by dissolving MA (79.48 mg, 0.685 mmol) in D2O (9883.38 mg, 493.488 mmol). Since this MOF (ZIF-8) is digested using D2SO4 (for qNMR purposes), we prepared the calibration curve by addition of a representative amount of D2SO4. The weighed mass of each compound can be found in Table .