Application of disposable starch-based platforms for sample introduction and determination of refractory elements using graphite furnace atomic absorption spectrometry and direct solid sample analysis
This study describes a new approach for direct solid sample analysis using thermoplastic starch (TPS) platforms for the determination of Mo and V by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). The TPS platform was prepared from a mixture of commercial corn starch (28% amylase and 72% amylopectin), with sorbitol as the plasticizer in a 70/30 mass-based ratio. Different parameters affecting the film composition, such as the proportion and plasticizer type, were evaluated taking into account the behavior in the graphite tube when the TPS platform was subjected to the heating program. The new sample introduction approach has been shown to increase the lifetime of the graphite tube significantly due to a much less pronounced tailing of the absorbance signals of elements such as Mo or V, which makes it possible to reduce atomization and cleaning times, compared to the use of a conventional graphite platform. Memory effects were significantly reduced using the starch-based platform, resulting in improved precision. The detection limit and characteristic mass were determined to be 25 pg and 7 pg for Mo, and 130 pg and 18 pg for V, respectively. The accuracy was confirmed by the analysis of a series of certified reference materials, including bovine liver, beef liver, rice flour and urban dust for Mo, and coal, urban dust, lichen and particulate matter for V.