can you look this paper. Up to Date Methods for the Determination of Rhenium O. V. Evdokimova, N. V. Pechishcheva, and K. Yu. Shunyaev., Journal of Analytical Chemistry, 2012, Vol. 67, No. 9, pp. 741–753.
We are working in optimization of the method with ICP-SFMS (mode High Resolution) for measurement Re. The results are good.