using forms of beta-leucine and leucine that contain several deuterium atoms in place of several hydrogen atoms as internal standards , techniques have been developed which make it possible to detect and quantitate as little as 0.1 mumol/liter of beta-leucine or leucine in human serum and in incubations containing rat liver supernatant . beta-leucine was not detectable , i.e . less than 0.1 mumol/liter , in any sera from 50 normal human subjects or in any sera from 50 cobalamin-deficient patients .
C0011744
deuterium
C0020275
hydrogen