[en] PIXE (Particle Induced X-ray Emission analysis) has been established as a method of trace element analysis. This work compares the detection limits using 2.13 and 2.55 MeV protons with those attainable using ⁴He²+ -ions of energies 6.07, 7.00, 8.52 and 9.12 MeV as projectile. This comparison was carried out using three common aerosol substrates: Kimfol, Nuclepore and Teflon. The detection limits using protons or ⁴He²+ -ions were of the same order but the lower detection limits with ⁴He²+ -ions according to theory were not observed, largely due to a higher intensity of gamma-quanta being Compton-scatterd in the Si(Li) detector. An improvement of the experimental chamber making it more suitable for ⁴He²+ -ions should lower the detection limits using ⁴He²+ as projectile. (author)