Scientists in Russia have developed a sensor that can quickly detect harmful oxalate ions in food products and in field conditions.

Oxalates, which are the salts of oxalic acids, can cause liver stone disease to develop when present in high levels. Researchers from Lomonosov Moscow State University (MSU) have developed a material and a dye agent that can identify these oxalate ions by simply touching the sensor to the food sample.

The material, a modified silicon-titanium gel deprived of its liquid phase, resembles purple powder and consists of around 100 micrometre-sized particles. It loses this colour when it comes into contact with oxalate ions because the gel’s structure contains eriochrome cyanine, which forms stable colourless compounds with oxalate ions. This causes the coloured complexes with eriochrome cyanine to disintegrate and the material to lose colour.

Scientists used a Lambda 35 spectrophotometer to measure the sensor’s colour and determine the concentration of oxalate ions.

It is able to detect the presence of ions even if their concentration is four times lower than the permitted maximum level.

“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,” said MSU professor and author of the study Elena Morosanova.

The research team used dock leaves, spinach leaves, parsley, ground black pepper and ginger root in their testing. They tested each for oxalate ions using the new sensor and then compared the results with high-performance liquid chromatography, a method that accurately separates, identifies and quantifies each component of a sample. When they compared the two methods the scientists found the results to be similar, 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,” said Morosanova.

While the NHS estimates that more than one in ten people have gallstones in the UK, only a minority of people develop symptoms.

The study was published in the journal Sensors.