Continuum Source Graphite Furnace Atomic Research Articles

Simultaneous Determination of Cd and Fe in Beans and Soil of Different Regions of Brazil Using High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry and Direct Solid Sampling

A fast routine screening method for the simultaneous determination of cadmium and iron in bean and soil samples is proposed, using high-resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sampling. The primary absorption line at 228.802 nm has been used for the determination of cadmium, and an adjacent secondary line, at 228.726 nm, for iron. Fourteen bean samples and 10 soil samples from nine states all over Brazil have been analyzed. The limits of detection (3 sigma, n = 10) were 2.0 microg kg(-1) for Cd and 4.5 mg kg(-1) for Fe. The relative standard deviation ranged from 4 to 7% for Cd and from 5 to 28% for Fe, which is usually acceptable for a screening method. The accuracy of the method has been confirmed by the analysis of two certified reference materials; the results were in agreement with the certified values at a 95% confidence interval.

Determination of Lead in Coal Using Direct Solid Sampling and High-Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry

A method has been developed for the determination of Pb in coal using direct solid sampling (SS) and high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). The certified coal reference materials used in this study were ground in an agate mortar to particle size ≤50 µm. Mass aliquots between 0.1 and 1 mg were weighed onto pyrolytic graphite platforms, and inserted directly into the graphite tube. For pyrolysis temperatures lower than 600 °C, a continuous background due to radiation scattering at solid particles preceded the atomic signal, as the coal matrix could not be sufficiently eliminated under these conditions. An optimized pyrolysis temperature of 700 °C was adopted for Pb without the use of a modifier. The optimum atomization temperature was found to be 1700 °C. Under these conditions, interference-free determination could be performed with calibration against aqueous standards in 0.5% v/v HNO3. A total of six certified reference coal samples were analyzed, and the results obtained were all in good agreement with certified and informed values, respectively, according to a Student t-test at a 95% confidence level. A detection limit of 0.008 µg g−1 for Pb was obtained at the 217.000 nm resonance line, a value comparable to those obtained by other sensitive, but much more sophisticated techniques, showing that the absence of dilution in the SS-HR-CS GF AAS method allows at least equivalent detection performance.