Accurate determination of the rotation rate in the inner radiative zone (0.2 < r/Rsolar < 0.5) of the sun from helioseismic observations requires rotational frequency splittings of exceptional quality. Indeed, only low degree modes are sensitive to the dynamics of the deep interior. Low and intermediate degree splittings have been estimated from a variety of instruments as well as different data analysis procedures. It is therefore not surprising that these determinations present significant differences. We present a study of the three more common data sets used to infer the solar rotation rate, namely LOWL, GONG and SOI/MDI. Our purpose is to find the common features present in the three sets, in order to build a robust determination of the rotation rate in the solar interior. We also have analyzed the effect of using rotational splittings estimated by fitting an asymmetric profile rather than a symmetric Lorentzian as a model for the limit spectrum.