A mathematical correction method for spectral interferences on selenium in inductively coupled plasma mass spectrometry

Despite the fact that Se has six isotopes, its determination in biological samples by inductively coupled plasma mass spectrometry is seriously hampered by spectral interferences. The resolution of quadrupole mass analyzers is insufficient to resolve Se(+) from molecular species having the same nominal mass. A mathematical correction method based on signal ratio measurement of (78)Se(+)/(76)Se(+) and (78)Ar(+)(2)/(76)Ar(+)(2) is described. It allows us to correct for the argon dimer interference at m/z 78 and thus to determine Se down to the 1 mug/l level. The method was applied to the determination of Se in human serum. Good agreement with the certified value was obtained.