The primary ion beam column of a combined secondary ion/sputtered neutral mass spectrometer is used forinsituion implantation of precise amounts of a given species superimposed as an internal standard upon its residual concentration. Subsequent depth profile analysis is done in the instrument after switching to another primary projectile. It is shown that concentrations can be determined with an accuracy of 4% from the knowninsituimplanted fluence by comparing the original and the added amounts. In this way, the helium concentration in a silicon sample (produced by external implantation) and the interfacial oxygen concentration between an amorphous and crystalline Si layer are determined quantitatively.