Artigo de Periódico
Unusual calibration curves observed for iron using high-resolution continuum source graphite furnace atomic absorption spectrometry
Autor
Welz, Bernhard
Santos, Lisia Maria Gobbo dos
Araujo, Rennan Geovanny Oliveira
Jacob, Silvana do C.
Vale, Maria Goreti R.
Okruss, Michael
Ross, Helmut Becker
Welz, Bernhard
Santos, Lisia Maria Gobbo dos
Araujo, Rennan Geovanny Oliveira
Jacob, Silvana do C.
Vale, Maria Goreti R.
Okruss, Michael
Ross, Helmut Becker
Institución
Resumen
The simultaneous determination of cadmium and iron in plant and soil samples has been investigated using
high-resolution continuum source graphite furnace atomic absorption spectrometry. The primary cadmium
resonance line at 228.802 nm and an adjacent secondary iron line at 228.726 nm, which is within the
spectral interval covered by the charge-coupled device (CCD) array detector, have been used for the
investigations. Due to the very high iron content in most of the soil samples the possibility has been
investigated to reduce the sensitivity and extend the working range by using side pixels for measurement at
the line wings instead of the line core. It has been found that the calibration curves measured at all the
analytically useful pixels of this line consisted of two linear parts with distinctly different slopes. This effect
has been independent of the positioning of the wavelength, i.e., if the Cd line or the Fe line was in the center
of the CCD array. The most likely explanation for this unusual behavior is a significant difference between the
instrument width ΔλInstr and the absorption line width ΔλAbs, which is quite pronounced in the case of Fe.
Using both parts of the calibration curves and simultaneous measurement at the line center and at the wings
made it possible to extend the working range for the iron determination to more than three orders of
magnitude.