Iron compounds catalyze the oxidation of 10-formyl-5,6,7,8 tetrahydrofolic acid to 10-formyl-7,8 dihydrofolic acid

It is shown how to calculate random errors in chemical shift tensor components and in the Euler angles which fix the orientation of the sigma tensor in the molecular frame, as obtained from spinning sideband analysis of MAS NMR spectra of powdered solids, when heteronuclear dipolar coupling interactions occur in a two spin system. The procedure was applied to experimental data corresponding to the chemical shift tensor of a carbon-13 bonded to a phosphorus-31 nucleus. Clues are given concerning the experimental variables to be set in order to obtain the desired accuracy in the orientation angles.