Precision mass measurements of highly charged ions

The reputation of Penning trap mass spectrometry for accuracy and precision was established with singly charged ions (SCI); however, the achievable precision and resolving power can be extended by using highly charged ions (HCI). The TITAN facility has demonstrated these enhancements for long-lived ($T_{1/2}\geq$50 ms) isobars and low-lying isomers, including $^{71}$Ge$^{21+}$, $^{74}Rb^{8+}$, $^{78}$Rb$^{8+}$, and $^{98}$Rb$^{15+}$. The Q-value of $^{71}$Ge enters into the neutrino cross section, and the use of HCI reduced the resolving power required to distinguish the isobars from 3 $\times$ 10$^5$ to 20. The precision achieved in the measurement of $^{74}$Rb$^{8+}$, a superallowed $\beta$-emitter and candidate to test the CVC hypothesis, rivaled earlier measurements with SCI in a fraction of the time. The 111.19(22) keV isomeric state in $^{78}$Rb was resolved from the ground state. Mass measurements of neutron-rich Rb and Sr isotopes near A = 100 aid in determining the r-process pathway. Advanced ion manipulation techniques and recent results will be presented.