In order to determine traces of boron, silicon and sulfur, B(18O, x)27Mg, Si(18O, x)43Sc and S(18O, x)47V reactions have been investigated between 15 and 44MeV. At 34 MeV, only a few of the systematically identified nuclear interferences
produce27Mg and the detection limit is 30ng boron for a 10 minute irradiation with a 0.3μA·cm−2 oxygen-18 beam. Silicon analysis has shown nuclear interferences from Al, P and K; interference-free detection limit is 80
ng silicon for an hour irradiation with a 0.4 μA·cm−2 beam at 39 MeV. There is no nuclear interference for the sulfur determination and the detection limit is 5 ng sulfur for
a 30 minutes irradiation with a 0.5 μA·cm−2 beam at 39 MeV. Thus a selective and sensitive sulfur determination can be achieved.