85Rb has 37 protons and 48 neutrons.
85Rb is a stable isotope.
The mass excess of 85Rb is -82167.34065 with an uncertainty of ±0.005.
The mass was measured using a Penning Trap and the related equations include:
Influence Equations
65.9% 86Kr-85Rb 1
34.1% 85Rb-84Kr 2
Reference
1. Yadernaya Fizika (Russia)
R.A. Demirkhanov, V.V. Dorokhov, M.I. Dzkuya, G.A. Dorokhova