Comparison of SIMS (top) and GD-MS (bottom) analyses on sample R6-2b (implanted B). dc HR-GD-MS can be used for depth profile analysis of impurities in PV Si with good sensitivity and a depth resolution of 0.5 μm. Concentration profiles of samples contaminated with B, P and Ti agreed well with implanted levels. For fast diffusing transition elements, e.g. Fe and Cu, different impurity distribution mechanisms occur. This should be taken into account when analysing these impurities.