Pesticide spotter

Chemists working at ETH Zurich have developed a new method to detect pesticide residues in foodstuffs.

A year ago they showed that they could analyse samples of fruit using mass spectrometry, but the system had a drawback - any pesticides needed to be extracted before they could be analysed in the spectrometer.

To avoid this time-consuming process, the researchers have now built an atmospheric pressure glow-discharge source (APGD source), an electric source that generates a plasma, or ionised gas, at atmospheric pressure.

When aimed at a piece of fruit peel, the plasma stream detaches molecules from the surface of the peel.

These are then transferred directly into the mass spectrometer, which can then be used to identify any chemical substances present in the fruit.

Although the method can determine chemical compounds faster than before, it cannot quantify the amounts identified.

Currently, the method can be used for preliminary probing – if pesticide residues are then found, conventional methods can be used to quantify how much have been discovered.

Nevertheless, it could perform quality checks on a running basis.

Various foodstuff samples could, for example, be analysed on a moving belt by the mass spectrometer.

The method is also attractive for forensic and medical purposes.

For example, traces of drugs or explosives on surfaces could be detected or human sweat and breath analysed.