A very high sensitivity, quadrupole-based inductively coupled plasma mass spectrometer (ICP-MS) has been developed and employed to measure very low concentrations (pg/L) of various actinides in solution. The detection capabilities of the instrument are shown using a variety of sample introduction methods, including simple direct sample nebulization, higher efficiency sample nebulization, and column preconcentration. This allowed three sigma detection limits in the range from 33 to 0.07 pg/L to be achieved, using short integration times, for a number of actinides. In addition, the improved sensitivity allowed isotope ratio measurements to be undertaken with good precision, (0.05 to 0.2%) at low concentrations (0.5 to 5 μg/L), without requiring long acquisition times. The results of isotope ratio measurements on silver, lead, and NIST natural lead standard SRM981 will be reported.