The observation of quadrupolar nuclei (spin > 1/2) in zero-field NMR is challenging due to their additional electric influence on reorientation of nuclei that can cause fast relaxation . Previous studies show that even though signals from the J-coupling to D, 14 N, and 35/37 Cl nuclei may not be directly visible in zero-field spectra, they may cause additional line-broadening . Conversely, in the study on zero-field NMR of quadrupolar nuclei, peaks originating from J-coupling interactions of 1 H-D and 1 H-14 N are demonstrated in J-spectra of ammonium isotopologues . Due to relatively small electric moment of D, and high local symmetry of 14 N-ammonium resulting in small nuclear quadrupolar interactions, the detection of J-coupling interactions of such nuclei in zerofield NMR is feasible . Our results demonstrate that zero-field NMR is able to detect 1 H/D isotopologues of urea molecules as well as provide information on 1 H/D ratio in a solution through simulation of J-spectrum. We also show that J-spectra for the complex molecules with more than two heteronuclei can be interpreted clearly by analyzing the energy structure of each small spin subgroup separately.