Determination of aluminium in nickel-based alloy samples using a longitudinal Zeeman-effect correction transversely heated graphite atomizer and a deuterium background correction end-heated graphite atomizer in electrothermal atomic absorption spectrometry

Abstract

A method for the accurate determination of aluminium in nickel-based alloys has been developed. The technique includes the microwave decomposition of samples followed by analysis with electrothermal atomic absorption spectrometry (ETAAS). Longitudinal Zeeman-effect correction with a transversely heated graphite atomizer (Zeeman-THGA) and deuterium background correction with an end-heated graphite atomizer (Deuterium-HGA) were used. The effects of various modifiers including (NH₄)₂HPO₄ , NH₄H₂PO₄ , Mg(NO₃)₂ , Pd+Mg(NO₃)₂ , NH₄NO₃ , AgNO₃ , KNO₃ , K₂Cr₂O₇ , ethylenediaminetetraacetic acid and Triton X-100 on the atomization of aluminium were studied. Of these, phosphate were relatively more effective than the other modifiers in terms of the optimization of sensitivity and minimization of the background absorption. The proposed methods were evaluated by determining aluminium contents in five certified reference materials of nickel-based alloys with aluminium contents ranging from 0.1127 to 5.5%. The best results were obtained with the (NH₄)₂HPO₄ . Zeeman-THGA and Deuterium-HGA gave comparable accuracy and precision. The characteristic masses for Zeeman-THGA and Deuterium-HGA were 27 and 8.2 pg, respectively. This indicated that Deuterium-HGA was more sensitive than Zeeman-THGA. The detection limits for these two background correction systems were 9.6 and 22 pg, respectively. The precision obtained with both background corrections ranged from 0.7–2.0%.