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MS-200 Application Note - Food analysis

The MS-200 can be used as an electronic nose. It's fast response time and high sensitivity are key requirements for this application.

We have run some preliminary tests on different samples to see if the MS-200 is delivering a response that can be used for further analysis. The MS-200 delivers us a mass peak of different height for the full mass range. This means we will have up to 300 data points with different values for the analysis.

The samples we have analysed were two different sorts of coffee, peppermint tea and some shrimps were already a "bit" smelly. Before every sample we took a background reading of cleaned air. We than sucked some gases of the headspace of the samples over the inlet membrane of the spectrometer. We waited for typically 1-2 minutes before we analysed the sample. After analysis the sample was removed and the background reading was checked for recovery.

Spectrum
Picture 1.1 Background sample

Spectrum
Picture 1.2 Peppermint Tea

The first sample to be analysed was peppermint tea. Picture 1.1 shows the background reading of the spectrometer, and picture 1.2 shows the analysis of the sample.

One can clearly see a distinct difference between the background and the sample. Only the mass range from 45 to 170 amu is displayed, as this shows the most significant difference and is not interfered with the standard peaks that are present in the ambient air.

The second experiment was performed to see if we could distinguish different samples that are similar. We therefore chose two different sorts of coffee. One of which was "Tesco Kenyan Coffee". The sample spectrum is shown in picture 2.1. The second sample was "Tesco Espresso" . The sample spectrum of this coffee is shown in picture 2.2.

Spectrum
Picture 2.1 Tesco Kenyan Coffee

Spectrum
Picture 2.2 Tesco Espresso

On the first glance the two spectra look very similar. However, there is a difference in the group pattern of the group between 65 and 70 amu, the peaks around 80 amu and the group around 108 amu.

The last two samples have been extremely dry. Therefore the next sample had a quite high moisture contents. We tried to analyse shrimps that are three days old. Again picture 3.1 shows the background reading and picture 3.2 shows the analysis.

Spectrum
Picture 3.1 Background

Spectrum
Picture 3.2 Shrimps

One can clearly see a group of peaks appearing between 45 and 70 amu. There is also a significant peak at 94 amu.

Conclusions

These preliminary experiments show that there is definitely a potential for the MS-200 to be used in food analysis. We can smell different kinds of food as well as distinguish between two different sorts of coffee. We also saw that we can measure moist samples. However, we tried to smell different sorts of whiskey and the huge amount of alcohol and water flooded our vacuum, which took us approximately 15 minutes to recover. Now there is definitely a need to investigate further the capabilities of the MS-200 by running more samples. This will give us a better feel for the different sort of response we can expect when analysing flavours.

Additional work has to be done to the software. The MS-200 software was tailored to enable the identification of unknowns and calculate concentrations of known mixtures of gases. It is not suitable for identifying the different peak patterns we want to analyse when using the MS-200 as an electronic nose. However there are suitable software packages available that could be readily adapted to handle the signal delivered by our time of flight mass spectrometer.


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Last updated: Friday, October 07, 2005, 17:22

Kore Technology Limited 2005