Spectral interferences in inductively coupled plasma atomic emission spectrometry—III. An assessment of OH band interferences using the ratio of the limit of determination and the limit of detection as a rational criterion

Abstract

Potential OH band interferences were studied for over 100 prominent lines emitted by an inductively coupled plasma (ICP). The basic information was derived from stepped spectral scans obtained with a 1.5-m echelle monochromator with predisperser ( Spectrochim. Acta 39B 1239 (1984)). The scans were made at both “high resolution” (HR) and “medium resolution” (MR) corresponding to spectral bandwidths of 4–5 pm and 11–16 pm, respectively. The seriousness of OH band interferences was assessed on the basis of the ratio of the limit of determination ( c D) and the limit of detection ( c L) as defined in Parts I and II ( Spectrochim. Acta 40B, 1085,1107 (1985)). It is shown that the results of an assessment based on this criterion do not strongly depend on the ICP operating conditions. Results are presented for a conventional argon ICP operated under compromise conditions. Appraisals are stated in generalized form for spectral bandwidths of 5 and 15 pm, independent of the apparatus used in this work. Out of the more than 100 prominent lines examined 7 were found to experience very serious OH band interference ( c D/ c L ⩾ 30) at 5 and/or 15 pm bandwidth. Serious interference (10 ⩽ c D/ c L ⩽ 30) at 5 and/or 15 pm bandwidth was established for 18 lines. OH band interference turned out to be non-existent or negligible for 83 prominent lines. The study also revealed that generally in the case of line overlap it is the limit of determination rather than the limit of detection that should be used as the criterion for the optimization of the ICP parameters.