New fast test method developed
of testing and analysing large numbers of food samples quickly for
possible pathogen contamination.
Processors are constantly on the look out for ways to speeding up the testing of large numbers of products. The faster the test, the quicker they can get product out the door and on to the supply chain. The research team for the lastest study was led by Renato Zenobi, a professor of analytical chemistry at ETH Zurich. Their new method is based on tests using what is called a "quadruple time-of-flight" (QTOF) mass spectrometer, a now standard laboratory instrument used for detecting pathogens on surfaces. The new analysis procedure represents a further development of the method recently published by the group in which the researchers showed they could quickly detect various substances in a simple manner, they claim. "Using their enhanced method, they can now also very precisely track down substances on surfaces of any kind," according to an ETH Zurich statement. Zenobi stated that samples for the mass spectrometry method are normally processed in solution. The solution is first electrosprayed, with the additional aid of a desolvation gas. The tiny droplets give rise to ions that are characteristic of the substance to be analysed and which the QTOF instrument measures. The ETH Zurich researchers have now almost turned the principle on its head, they claim. Instead of studying the substances in the solution, they developed a method to examine the substances present in the desolvation gas assisting the spray. With the newly-developed method nitrogen is blown from a small nozzle onto a sample surface. As the gas strikes the surface it desorbs semi-volatile substances. The enriched gas stream is then fed into the mass spectrometer where the absorbed substances can be precisely analysed, they stated. "There is nothing special about the new method from a technical viewpoint," Zenobi stated. Huanwen Chen, who developed the method during his post-doctoral studies in Zenobi's group, demonstrated this when together with his supervisor he presented the new method to an unnamed company. Within one hour Chen had modified their mass spectrometer so that it could be used to analyse the surface of any kind of object, according to Zenobi. "One particular strength of our approach is that even the surfaces of living organisms can be examined," he stated. "It only takes a few seconds to measure a single sample, so large numbers of random samples can be routinely analysed." For meat samples the scientists were also able to show that the sample material does not even need to be thawed. "In view of the numerous possible applications, it is not surprising that the new method is of interest not only to foodstuffs technologists and safety experts but also to medical professionals and drugs investigators in sport," Zenobi stated. The research is published in the latest issue of the scientific journal Angewandte Chemie.