Unique Material Detects Presence of Toxic Ions in Food Items

MSU-based researchers have created a new material based on a silicon-titanium gel and a dye agent. The material is able to rapidly identify if detrimental oxalate ions are present in food products even in field conditions.

No further operations on the subject of study are necessary to conduct such investigation. To examine a sample, one just has to touch it with the new material, and this is what makes it exceptional. The results of the research have been published in the Sensors journal.

The salts of oxalic acids are called oxalates. A majority of them are poorly soluble in water and are distilled from solutions in the form of crystals. There is a danger of liver stone disease development if the levels of oxalate in food are high. The researchers developed an extremely sensitive material: it can identify the presence of risky ions even if their concentration is four times below the permitted maximum level.

The new sensor is an adapted silicon-titanium gel deprived of its liquid phase. The material resembles purple powder comprising about 100 mkm-sized particles. The gel’s structure also includes eriochrome cyanine—an indicator that loses its color after touching any substance containing oxalate ions. This reaction is elucidated by the fact that titanium added into the matrix of the sensor material can form stable colorless compounds with oxalate ions resulting in colored complexes with eriochrome cyanine to crumble and the material to lose color. The researchers employed a Lambda 35 spectrophotometer to measure the intensity of sensor material coloring that specifies the concentration of ions.

The researchers used the sol-gel technology to attain this sensor material. According to that technology, first a solution with insoluble particles (1 to 100 nm) is made, and then the liquid phase is removed from it. After the removal of liquid, solid molecules begin building up new bonds, and the 3D molecular matrix transpires. After the synthesis process was finished, the team incorporated eriochrome cyanine to it.

Identifying oxalate ions in biological liquids, first of all, in urine is an important task. To be able to do it we need to create a sensor material with higher sensitiveness. This is the goal of our further studies.

Elena Morosanova, Study Author & Professor at the Department of Analytical Chemistry of the Faculty of Chemistry, MSU

The researchers chose five samples of food products as test objects: dock leaves, ground black pepper, parsley, spinach leaves, and ginger root. The content of oxalate ions in these samples was established in two ways: using the sensor material and extremely efficient liquid chromatography. The technique revealed almost similar results with the variance amounting to less than 10%.

"Our sensor material helps determine the presence of oxalate ions in food products—simply, quickly, and off the lab," added Elena Morosanova.

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