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A team of scientists from MSU developed a new material based on silicon-titanium gel and a dye agent. The material is able to quickly identify the presence of harmful oxalate ions in food products even in field conditions. No additional operations with the subject of study are required to conduct such analysis. To analyze a sample, one simply has to touch it with the new material, and this is what makes it unique. The results of the study were published in the Sensors journal.

Oxalates are the salts of oxalic acids. Many of them are poorly soluble in water and are distilled from solutions in the form of crystals. When the levels of oxalate in food are high, there is a risk of liver stone disease development. MSU-based scientists created a highly sensitive material: it can identify the presence of harmful ions even if their concentration is four times lower than the allowed maximum level.

The new sensor is a modified silicon-titanium gel deprived of its liquid phase. The material looks like purple powder consisting of about 100 mkm-sized particles. The structure of the gel also includes eriochrome cyanine - an indicator that loses its colour after contacting any substance with oxalate ions in it. This reaction is explained by the fact that titanium included into the matrix of the sensor material can form stable colourless compounds with oxalate ions causing coloured complexes with eriochrome cyanine to disintegrate and the material to lose colour. The scientists used Lambda 35 spectrophotometer to measure the intensity of sensor material colouring that indicates the concentration of ions.

To obtain this sensor material, the scientists used the sol-gel technology. According to it, first a solution with insoluble particles (1 to 100 nm) is prepared, and then the liquid phase is removed from it. After the removal of liquid solid molecules start building up new bonds, and the 3D molecular matrix occurs. After the synthesis process was completed, the scientists added 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," - says Elena Morosanova, the author of the study and professor at the department of analytical chemistry of the Faculty of Chemistry, MSU.

The scientists selected five samples of food products as test objects: dock leaves, spinach leaves, parsley, ground black pepper, and ginger root. The content of oxalate ions in these samples was determined in two ways:using the sensor material and highly efficient liquid chromatography. The method showed almost similar results with the difference 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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