Muon capture on N not equal Z nuclei is discussed within an algebraic appro
ach in the frame of the version 3 of the interacting boson model (IBM) of n
uclear structure, thus including the isospin degree of freedom. A simple fo
rmula for the capture rate is worked out and compared with experimental dat
a. Inclusive measurements are suggested in order to verify the validity of
an IBM-4 supersymmetry scheme for the sd-shell nuclei.