The use of 2-2-thiazolylazo-p -cresol to minimize the interference of Ni and Cu for the bismuth determination in alloys by hydride generation atomic absorption spectrometry Iracema Takase a , Aderval S. Luna b , Reinaldo Calixto de Campos c, * a Department of Analytical Chemistry, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil b Department of Analytical Chemistry, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil c Department of Chemistry, Pontifı ´cia Universidade Cato ´lica do Rio de Janeiro, Rio de Janeiro, Brazil Received 4 February 2003; received in revised form 8 May 2003; accepted 14 May 2003 Abstract Thiazolylazo p -cresol (TAC) was studied as a masking agent for the determination of Bi in rich Ni and Cu alloys by hydride generation atomic absorption spectrometry (HGAAS). In the presence of TAC, Bi/Ni and Bi/Cu ratios up to 1:160 000 and 1:16 000, respectively, were found to be tolerable. No buffering was necessary once the masking agent was effectiveeven in very acid medium. Limits of detection at the low mgg 1 range were reached and the accuracy of the procedure was confirmed by the good concordance between found and certified values in the analysis of certified reference materials (CRM). # 2003 Elsevier B.V. All rights reserved. Keywords: Bismuth; Ni and Cu alloy, masking agent; Hydride generation atomic absorption spectrometry 1. Introduction Bismuth is a harmful impurity for several metals and alloys and its concentration should be con- trolled at the mgg 1 level [1]. Zhou et al. [2], for example, reported a substantial decrease in the hot ductility of steel if it contains more than 6 mgg 1 of Bi while Welz et al. [3] reported that steel can break up if it contains more than 0.0002% of Bi. Also, the presence of certain trace elements (including Bi) in nickel metal can lead to detri- mental effects on its properties, and analytical methods of suitable sensitivity, precision, and speed are needed for the quality control of nickel specifications [4]. Due to its simplicity and sensitivity, hydride generation atomic absorption spectrometry (HGAAS) has been intensively used to determine elements that form volatile hydrides in several matrices [1,3,5,6]. However, condensed phase in- terferences may impair its application for the analysis of transition metals rich samples such as some alloys. Consequently, several methods have been proposed to minimize these interferences. * Corresponding author. Fax:  /55-21-3114-1309. E-mail address: rccampos@rdc.puc-rio.br (R.C. de Campos). Talanta 61 (2003) 597  /602 www.elsevier.com/locate/talanta 0039-9140/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0039-9140(03)00365-5