A shift of the NMR line proportional to the z component of the magnetization caused by the presence of a strong dipolar field is a well documented phenomenon and is observed in NMR of liquids. In the case of hyperpolarized solids the line shift effect due to the dipolar field is usually rationalized through the theory of moments. Indeed, a direct measurement of the 1 H line shift is difficult and inaccurate in these DNP experiments because the determination of the location of the maximum intensity is prone to large errors on such broad and possibly non symmetrical lines. Therefore, the first moment, or center of gravity of the resonance line provides a measure of the NMR line shift, which is identical to the shift of its maximum in the case of a symmetrical line shape. It is defined as: