Sequential determination of Cd and Cr in biomass samples and their ashes using high-resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sample analysis

High-resolution continuum source graphite furnace atomic absorption spectrometry, because of the use of only one radiation source for all elements, offers the possibility of sequential determination of two or more elements from the same sample aliquot if their volatilities are significantly different Cd and Cr were determined sequentially in samples of biomass and biomass ashes employing direct solid sample analysis. The use of a chemical modifier was found to be not necessary, and calibration could be carried out using aqueous standard solutions. A pyrolysis temperature of 400 degrees C and an atomization temperature of 1500 degrees C were used for the determination of Cd; no losses of Cr were observed at this temperature. After the atomization of Cd the wavelength was changed and Cr atomized at 2600 degrees C. The limits of detection (LOD) and quantification (LOQ) were 1.1 mu g kg(-1) and 3.7 mu g kg(-1), respectively, for Cd and 21 mu g kg(-1) and 70 mu g kg(-1), respectively, for Cr using the most sensitive line at 357.869 nm, or 90 mu g kg(-1) and 300 mu g kg(-1), respectively, using the less sensitive line at 428.972 nm. The precision, expressed as relative standard deviation was around 10%, which is typical for direct solid sample analysis. The values found for Cd in biomass samples were between <1.1 mu g kg(-1) and 789 mu g kg(-1), whereas those for Cr were between 7.9 mg kg(-1) and 89 mg kg(-1); the values found in the ashes were significantly lower for Cd, between <1.1 mu g kg(-1) and 6.3 mu g kg(-1), whereas the trend was not so clear for Cr, where the values were between 3.4 mg kg(-1) and 28 mg kg(-1). (c) 2013 Elsevier B.V. All rights reserved.