HPCE was shown to be an effective and convenient method for the determination of nicotinamide-adenine dinucleotide (oxidized, NAD(+); reduced, NADH), nicotinamide-adenine dinucleotide phosphate (oxidized, NADP; reduced, NADPH) and their synthetic derivatives. The coenzymes were easily separated among themselves and from their degradation products, which are inhibitors of dehydrogenases, in 15 min in a coated capillary. Several coenzyme derivatives such as N-6-(2-aminoethyl)-NAD(P)(+) and N(1)-(2-aminoethyl)-NAD(P)(+) were separated by zone electrophoresis in uncoated or coated capillaries using 50 mM 3-(N-morpholino)propane-sulphonic acid (pH 7.0) or Tris-HCl (pH 8.0) as buffer systems. Capillary zone electrophoresis and micellar electrokinetic capillary chromatography can also be used to monitor continuously coenzyme chemical modifications .