Impact of the analytical blank in the uncertainty evaluation of the copper content in waters by flame atomic absorption spectrometry.
Chemical analysts use analytical blanks in their analyses, but seldom is this source of uncertainty evaluated. Generally, there is great confusion. Although the numerical value of the blank, in some situations, can be negligible, its source of uncertainty cannot be. This article discusses the uncertainty contribution of the analytical blank using a numerical example of the copper content in waters by flame atomic absorption spectrometry. The results indicate that the uncertainties of the analytical blank can contribute up to 50% when the blank sample is considered in this analysis, confirming its high impact. This effect can be primarily observed where the analyte concentration approaches the lower range of the analytical curve. Even so, the blank is not always computed. Therefore, the relevance of the analytical blank can be confirmed by uncertainty evaluation.
PETROBRAS TRANSPORTE S.A., Gerência Geral de Engenharia, Av. Pres. Vargas, 328, 20091-060 Rio de Janeiro, RJ, Brazil. elciooliveira@petrobras.com.br
Elcio Cruz
EC
de Oliveira
Maria Inês Couto
MI
Monteiro
Fernanda Veronesi Marinho
FV
Pontes
Marcelo Dominguez
MD
de Almeida
Manuel Castro
MC
Carneiro
Lílian Irene Dias
LI
da Silva
Arnaldo
A
Alcover Neto
D003300:Copper / Q000737:chemistry*; D013054:Spectrophotometry, Atomic / Q000379:methods*; D035501:Uncertainty; D014867:Water / Q000737:chemistry*
D014867:Water; D003300:Copper