GC/TOF MS application: Food analysis
Trace component analysis of food stuffs using GC/TOF MS (BenchTOF-dx) and TargetView
 Both product safety and quality, typically relating to flavour composition, taints and contamination, are of concern in the food industry, with many regulations in place to control these. As such, manufacturers are keen to quickly and simply identify compounds of interest.
TargetView software has been specifically designed to speed up and improve the identification of target compounds by comparing defined library spectra with sample spectra. As an example of its application here, samples of potato chips have been analyzed to identify selective pyrazine (flavour) compounds.
Analysis of pyrazines (flavour compounds) in crisps
For this application the flavour compounds (pyrazines) in potato chips (crisps) were studied. In order to extract the flavour compounds of the potato chips a Markes International Micro-Chamber/Thermal Extractor™ (µ-CTE™) was used with the flavour compounds collected onto thermal desorption tubes.
The thermal desorption tubes were subsequently analysed in a Markes International UNITY 2™ thermal desorption unit coupled with an Agilent Technologies GC and ALMSCO BenchTOF-dx time-of-flight mass spectrometer (TOF MS).
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Extraction/Sampling
- Micro-chamber temp: 40°C
- Flow rate: 40 mL/min
- Emissions collected for 10 min onto Tenax® TA sorbent tubes (25 min equilibration time and 10 min sampling time)
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Thermal desorption conditions:
- Desorption temperature: 300°C for 5 min.
- Trap low - 0°C, Trap high 320°C, 5 min.
- Trap: General purpose trap
- Split: Single split 20:1
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GC conditions:
- Oven 60 °C for 2 min, then 20 °C/min to 240 °C, hold for 2 min
- Total run time 14.5 min
- Column: HP-INNOWax Polyethylene Glyco
30 m x 250 µm x 0.25 µm
- Constant flow mode
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BenchTOF-dx conditions:
- Mass range: 45 - 400 amu
- Transfer line: 250°C
- MS source: 200°C
- Data rate: 2 Hz (5000 spectral summations per data point)
- Source voltage: 1.70 V
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Results from potato chip analysis
- The fast data acquisition of BenchTOF-dx produces comprehensive spectral information with high sensitivity. Its software also applies ‘dynamic background compensation’ to eliminate noise ions, resulting in ‘cleaner’ data which facilitates compound identification.
- TargetView analysis of the data was run against a library of selective pyrazines, in which a number of pyrazines (2,3 dimethyl pyrazine, 2-ethyl, 5-methyl pyrazine and 2,6 diethyl pyrazine) were shown present in the sample
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Above: Pyrazine target compound identification from potato chips (crisps). Trace level detection of 2,5-dimethyl pyrazine highlighted
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Expanded view (top) showing three (3) very small red bars indicating trace-level detection of 2,5 dimethyl pyrazine, 2-ethyl, 5-methyl pyrazine and 2,6 diethyl pyrazine. This is also confirmed with a cross reference against the NIST database
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Conclusions
The technique used here has effortlessly generated a list of target pyrazines found in potato chips. The clear spectral data produced by BenchTOF-dx is ideal for target compound identification by TargetView.
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