Spectral interferences in inductively coupled plasma atomic emission spectrometry—II: An experimental study of the effect of spectral bandwidth on the inaccuracy in net signals originating from wavelength positioning errors in a slew-scan spectrometer

Abstract

This article deals with an evaluation of the error in net analyte signals resulting from wavelength positioning errors in a slew-scan monochromator in the event that the analysis line experiences line overlap. The theoretical part concerns the development of an error function and the introduction of the concepts of “10% inaccuracy limit” ( c 10/ c L ) and “find peak transition” ( c FPT), where c L is the detection limit, c 10 the concentration at which the maximum error is 10 % and c FPT the concentration at which the analysis line shows just resolved from the interfering line so that a find peak routine can be used. The experimental part encompasses case studies for two levels of spectral resolution, designated “high resolution” (HR) and “medium resolution” (MR) as defined in a companion paper ( Spectrochim Acta 40B, 1085 (1985)) for a 1.5-m echelle monochromator with predisperser ( Spectrochim. Acta 39B, 1239 (1984)). The case studies refer to situations in which prominent lines of Al, Ca, V, Nb, Bi and Sn experience overlap with one or more OH band components. It was shown that HR can bring an advantage over MR amounting to a factor of 15 in c 10, e.g. for Al I 309.271 and Al I 308.216, but may also entail only a marginal profit, e.g. for Bi I 306.765/306.774 nm. The effects of the distance between analysis and interfering line and the signal-to-background ratio of the interfering line were studied systematically by applying computer techniques such us shifting of experimental line profiles along the wavelength axis. This study also implied the consideration of the relationship between the 10% inaccuracy concentration, c 10, and the limit of determination, c D , defined in the companion paper.