Sea quark and gluon polarization in the nucleon at NLO accuracy

We investigate the sea quark polarization in the nucleon by means of a combined next to leading order analysis to the recently enlarged set of inclusive and semi-inclusive polarized deep inelastic scattering data. Using the Lagrange multiplier method, we assess the uncertainty inherent to the extraction of the different spin-dependent parton densities in a QCD global fit and the impact of the increased set of semi-inclusive data now available. We comment on future prospects at Relativistic Heavy Ion Collider and the Thomas Jefferson National Laboratory and their potential impact in the future determination of polarized parton densities.