W+Rh as permanent chemical modifier in simultaneous atomic absorption spectrometry: interference studies on As, Cd, Pb and Se determination

Author(s)

Cassiana S Nomura ^[1] ; Paulo R. M Correia ^[2] ; Pedro V Oliveira ^[3] ; Elisabeth Oliveira ^[4]

Affiliation

^[1] Universidade de São Paulo. Instituto de Química - Brasil

^[2] Universidade de São Paulo. Instituto de Química - Brasil

^[3] Universidade de São Paulo. Instituto de Química - Brasil

^[4] Universidade de São Paulo. Instituto de Química - Brasil

• Document type: Journal article
• Source: Journal of the Brazilian Chemical Society; v. 15, n. 1, p. 75-82, 2004-02-00.
• Field of knowledge: Physical Sciences and Mathematics - Chemistry

Abstract

A systematic study of Na+, K+, Ca2+, Mg2+, Cl-, NO3-, SO4(2-) and PO4(3-) interference on the simultaneous atomization of As, Cd, Pb and Se was carried out using an electrothermal atomic absorption spectrometer. The mixture 250 mg W + 250 mg Rh was thermally deposited on the graphite tube platform and used as permanent chemical modifier. The compromised heating program adjustments (Tp = 650ºC and Ta = 2200ºC) diminished the thermal decomposition and volatilization efficiency of the interfering species during the pyrolysis step. The Cl- and SO4(2-) anions caused the most severe interference, while NO3- only affected the analytes' atomization when high amounts (> 27 mg) were used. The anion PO4(3-) produced a strong negative interference on the Se absorbance signals. The presence of Na+, K+, Ca2+ and Mg2+ prejudiced mainly Cd, and the interference effects of Cl- salts were more pronounced than NO3- salts. (AU)