Development of a commercial laser isotope ratiometer for food adulteration analysis

Stable isotope ratio analysis is recognized as a standard technique in the identification of adulterated foodstuffs. The procedure looks at the ratio of naturally occuring none radioactive heavy and light isotopes which go to make up a food product. The most common isotopes used in this process are 13C/12C and 18O/16O. Changes in the ratio’s between between the light and heavy isotopes can indicate both the origin of a food stuff and some of the process through which the food stuff has been exposed. A good example is honey. Sugars within a natural honey have a different 13C/12C ratio to honey that has been adulterated by the addition of exogenous sugar. This is a common form of adulateration that can be simply identified using stable isotope analysis.
Currently this analysis can only be achieved using high precision high value laboratory based instrumentation. This requires users to send samples of food stuffs to specialist laboratories located remotley from the site of production.
This process is both time consuming, costly and laborious, limiting the use and application of this powerful tool in the food industry.
With the development of laser based isotope systems, the instrumentation has become simpler and more reliable, even enabling the analysis of basic compounds, such as water, in a field situation. However current laser technology suffers from one significant limitation, the inability to perform chromatographic separation. This is a process that allows analytical instrumentation to separate out the components of complex mixtures, permitting their individual elements to be investigated. For instance, it may be necessary to look at the vanilla flavouring within a product to ensure it has come from a vanilla plant and not a synthetic analogue. This requires the vanilla compound to be separated from the rest of the food product, a process typically achieved by chromatography.
The STFC (Space Science & Technology Department) has developed and patented a laser isotope ratiometer with a number of key features which distinguish it from other laser isotope instruments including the ability to carry out isotope analysis over short time periods, typically in the millisecond range. This patented system will for the first time, allow laser systems to perform isotope analysis on chromatographically separated compounds.To demonstrate this ability and make the system field deployable, a robust and portable chromatographic interface sample inlet will be developed and integrated with the laser by Protium MS. The aim of this project is to develop a prototype laser based GC Isotope system which will allow on-site detection and quantification of food adulteration. The objectives of this project are to develop a chromatographic front end to integrate with the mechanics and electronics of the current patented laser system and to develop a laser isotope system.