  The $\eta$-$\eta^\prime$ pseudoscalar mixing angle and the gluonium content
of the $\eta^\prime$ meson are deduced from an updated phenomenological
analysis of $J/\psi$ decays into a vector and a pseudoscalar meson. In absence
of gluonium, the value of the mixing angle in the quark-flavour basis is found
to be $\phi_P=(40.7\pm 2.3)^\circ$. In presence of gluonium, the values for the
mixing angle and the gluonic content of the $\eta^\prime$ wave function are
$\phi_P=(44.6\pm 4.4)^\circ$ and $Z^2_{\eta^\prime}=0.29^{+0.18}_{-0.26}$,
respectively. The newly reported values of $B(J/\psi\to\rho\pi)$ by the BABAR
and BES Collaborations are crucial to get a consistent description of data.
