[Determination of trace arsenic in sulfur by graphite furnace atomic absorption spectrometry with La(NO3)3-Ni(NO3)2 matrix modifier].

In this paper, the decomposition method of sulfur and the determination of trace arsenic in sulfur by GFAAS with La(NO3)3-Ni(NO3)2 matrix modifier were studied in detail. The decomposition of sulfur with mixed acid HNO3-HClO4 by controlled temperature electrothermal method or pressure crucible method was efficient and safe. The sensitivity of the determination of arsenic with La(NO3)3-Ni(NO3)2 matrix modifier was higher than with Ni(NO3)2 or Mg(NO3)2 matrix modifiers. The detection limit was 0.034 microgram.mL-1 (k = 3). The analytical results of the sulfur samples were coincident with the results of determination by HG-ICP-AES. The adding recoveries were 97.5%-110% and the relative standard deviation was less than or equal to 2.1% (n = 4).