Studies of a low-noise laminar flow torch for inductively coupled plasma atomic emission spectrometry. Part 2. Noise power studies and interference effects

Abstract

Noise power spectra of emission signals from the laminar flow torch (LFT) designed in our laboratory and a conventional tangential flow torch (TFT) are presented and described. It is shown that the fundamental frequency of rotation in a conventional torch is completely removed in the laminar flow torch. Moreover, the use of an extended torch is essential in removing air entrainment effects and also for the maintenance of undisturbed laminar flow. The interference effects of phosphate and sodium on calcium emission are assessed in the laminar flow torch and compared with those in a conventional torch. Phosphate interference is not observed in the laminar flow torch while the effect of sodium on calcium emission is shown to be of the same magnitude in both torches.