Electrode Modified by Reduced Graphene Oxide for Monitoring of Total Thallium in Grain Products

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.