Analytical Sciences

Analytical Characteristics of a Continuum-Source Tungsten Coil Atomic Absorption Spectrometer

Jennifer A. RUST,* Joaquim A. NÓBREGA,** Clifton P. CALLOWAY, Jr.,*** and Bradley T. JONES*

*Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109, USA
**Departamento de Química, Universidade Federal de São Carlos, São Carlos, SP, Brazil
***Department of Chemistry, Physics and Geology, Winthrop University, Rock Hill, SC 29733, USA

A continuum-source tungsten coil electrothermal atomic absorption spectrometer has been assembled, evaluated, and employed in four different applications. The instrument consists of a xenon arc lamp light source, a tungsten coil atomizer, a Czerny-Turner high resolution monochromator, and a linear photodiode array detector. This instrument provides simultaneous multi-element analyses across a 4 nm spectral window with a resolution of 0.024 nm. Such a device might be useful in many different types of analyses. To demonstrate this broad appeal, four very different applications have been evaluated. First of all, the temperature of the gas phase was measured during the atomization cycle of the tungsten coil, using tin as a thermometric element. Secondly, a summation approach for two absorption lines for aluminum falling within the same spectral window (305.5 - 309.5 nm) was evaluated. This approach improves the sensitivity without requiring any additional preconcentration steps. The third application describes a background subtraction technique, as it is applied to the analysis of an oil emulsion sample. Finally, interference effects caused by Na on the atomization of Pb were studied. The simultaneous measurements of Pb and Na suggests that negative interference arises at least partially from competition between Pb and Na atoms for H₂ in the gas phase.

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