Characterization of a modified two-step furnace for atomic absorption spectrometry for selective volatilization of iron species in hemin

Abstract

A two-step furnace was modified by eliminating contact between the cup furnace and the integrated contact cuvette (ICC), thus maximizing the independence of the temperature control of the two components. Optimized cup and ICC temperatures were determined for Cd, Cr, Cu, Fe, and Pb. Efficient analyte transportation (⇀91%), from the cup to the ICC, was observed for an ICC–cup separation of up to 3 mm. Analyte transport was aided by an apparent convective flow of Ar into the hole in the bottom of the ICC. Despite this flow, the loss of Cd and Pb from the furnace appear to be limited by diffusion. The relative sensitivity for the modified two-step furnace was approximately 50% worse than that for the same ICC with atomization from a platform. Iron in a porphyrin complex (heme Fe) gave two absorbance peaks at approximately 300 °C and 2000 °C. Use of two-stage volatilization (the furnace temperature was held constant while the cup was heated to 300 °C and then 2000 °C) produced both peaks from a single atomization.