Abstract
Grain products and the associated industry have a notable economic and social impact all over the world. The toxicological safety of grain products is a nutritional prerogative. This study focused on the determination of thallium content in grain product samples collected from a commercial brand commonly available in Poland. The samples were analyzed with the use of differential pulse anodic stripping voltammetry (DPASV) with graphene oxide based on glassy carbon. The stripping anodic peak current of thallium was linear over its concentration range from 9.78 × 10−9 to 97.8 × 10−9 M. The limit of detection (LOD) was calculated according to the formula LOD = (κ × SDa)/b, where κ is 3.3, SDa is the standard deviation of the intercept, and b is the slope. The determined value of LOD was 1.229 µg L−1 (6.01 × 10−9 M). The proposed method was successfully applied for the determination of thallium ions in samples of actual grain products. The obtained results confirmed that thallium was present in the studied cereal samples (average content at 0.0268 ± 0.0798 mg/kg). Thallium has a half-life of 60 days; therefore, the consumption of foods with thallium content of approximately 0.08 mg/kg has the potential for harmful bioaccumulation in the body. Thallium contamination in cereal products should be a critical parameter for health environmental regulations.
Highlights
Flour and grain products are an important source of nutrients and, as such, are widely consumed in the majority of the world
The electrochemical reduction of GO is an effective and environmentally friendly method for the formation of graphene-like conductive structures. This process can be monitored by cyclic voltammetry (CV), considering the fact that electroreduction of oxygen-containing surface groups of GO gives rise to a more conductive and roughly reduced graphene oxide (RGO) material
The results suggest that the glassy carbon electrode (GC)/RGO electrode possesses a significantly increased electroactive surface
Summary
Flour and grain products are an important source of nutrients and, as such, are widely consumed in the majority of the world. Since flour is a commodity in the bread and bakery industry, its safety is of high nutritional and toxicological interest. Due to the high consumption rate of flour-based products, the presence of hazardous heavy metal, such as thallium (Tl), would be a significant health risk. The presence of contaminants comprising thallium in air results in its absorption by plants—a process that is further enhanced by high thallium content in soil [2,3]. Samples of clovers collected from uncontaminated regions of Poland contained 0.008–0.01 mg/kg thallium. There is little information regarding this subject, breads, cereals, pasta, and flour can contain thallium (Tl). Tl+ is known to interfere with Na+ /K+ ATPase and pyruvate kinase [6]
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