Abstract: Methods are provided for deuteration, tritiation, dedeuteration or detritiation of a carbonyl compound. A catalytic antibody that catalyzes an aldol addition reaction is contacted with a carbonyl compound to exchange at least one hydrogen atom of the carbonyl compound with a deterium or tritium atom of an isotopically enriched water molecule, or to exchange at least one deuterium or tritium atom of the carbonyl compound with a hydrogen atom. The aldol addition reaction may be between an aliphatic ketone donor and an aldehyde acceptor. Isotopically enriched water molecules include deuterium hydrogen oxide, dideuterium oxide, tritium hydrogen oxide, ditritium oxide and deuterium tritium oxide. The catalytic antibody may be that secreted by hybridoma 38C2 (ATCC HB 12005) or 33F12 (ATCC HB 12004).