Spectral and non-spectral interferences in the determination of selenium by inductively coupled plasma atomic emission spectrometry

Spectral and non-spectral interferences observed in the determination of selenium by ICP-AES were investigated in this study. The identity of the carbon-induced emission peak that interferes on the Se 196.090 nm analytical line was clarified. It was found that this peak was not a part of a CN band but most likely belongs to a spectral band emitted by the CO molecule. Non-spectral interferences of matrix elements C, S, P and Br assisting in the enhancement of selenium emission were found. Concentration dependences of these matrix effects were measured in the range of 0.5-20 g L-1 of the matrix element and 0.1-100 mg L-1 of Se. No enhancement of the Mg I 285.213 nm line was observed when the influence of these matrix elements on magnesium was monitored for comparison at the same time. The enhancement of selenium emission was about 50% in the most significant case (sulfur, 10 g L-1). A similar effect was observed when gaseous compounds of C and S were introduced into the ICP. The mechanism of this matrix effect was studied and partially clarified as being probably related to ionization of matrix elements.