High-resolution mass spectra illustrate the resolving power of our prototype NanoSims instrument. The detectors are positioned along the focal plane at the focal points for the atomic masses (a) 12, (b) 13, (c) 26, and (d) 27 as shown in Figure 14. Varying the electrical potential of the deflector plates selects between different isobaric ions. Note that with the log scale and the counting software, when zero counts are recorded, the data point is recorded as 1/T, where T is the counting time in seconds for each data point. In (a-c) the counting time was 0.5 sec, and the background count rate appears as 2 counts/sec even though it is zero counts; in (d), the counting time was 10 sec and a background count rate of zero is not visible. See Additional data file 6 for more details on the shape of the peaks.