Flow injection analysis (FIA) is a laboratory-based technique which is faster than liquid chromatography (HPLC) but less selective.
This paper (open access) builds on previous work to use high-throughput FIA-mass spectrometry (FIA-MS) fingerprinting of polyphenols to discriminate chicory from tea of various varieties, This previous work had failed to discriminate chicory adulteration in the cases of black or green tea.
The authors have repeated the approach but this time using tandem mass spectrometry (MS/MS). They built a database of the polyphenol fingerprint (55 polyphenols) from 100 tea samples (black, green, oolong, red and white) and from 20 chicory samples. Database samples were purchased from local markets, so were of unverified source or provenance. It is likely that this exercise of building the database would need to be repeated with verified samples if the test were to be validated for routine use. The authors reported excellent chemometric discrimination between the “fingerprints” from tea and chicory, which they were then able to use to detect down to 15% adulteration of tea with chicory.
The authors recommend a workflow where FIA-MS/MS is used as an initial high-throughput screen, with polyphenols in “suspicious” samples then confirmed by LC-MSMS.
For an overview of the difference between MS and MS/MS, see FAN’s analytical techniques explainer pages.
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