Italian researchers have developed a TLC plate that allows them to identify not only the presence of different components in a mixture, but also how much of each component is present.  

Chromatography is a versatile and powerful technique that separates mixtures into individual components according to their different binding affinities to a mobile and a stationary phase. Augusto Nascetti and colleagues at the University of Rome put the stationary phase of a TLC plate and amorphous silicon photodiodes on the same glass substrate to make the plate 'active' and allow real-time monitoring of the separation process.

In their technique, the team irradiate the plate with ultraviolet radiation while the chromatographic separation is taking place. This excites the fluorescence of the different components of the mixture being analysed. The intensity of the fluorescence signal is proportional to the peak height detected and this can be used to determine the quantity of each component in the mixture.

According to Nascetti the preliminary results 'suggest that the proposed system can effectively add value to conventional TLC technology'. The technique operates on a small scale and requires only small amounts of eluents, which reduces both the cost and any risks associated with the use of harmful solvents. Advantageously, the plate can also be easily incorporated into a portable field device. Potential applications include uses in food quality control such as early detection of toxins in wine.

Kathryn Lees