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Revisiting the caffeine-free status of rooibos and honeybush herbal teas using specific MRM and high resolution LC-MS methods
- Stander, Maria A., Joubert, Elizabeth, De Beer, Dalene
- Subtropical plant science 2019 v.76 pp. 39-43
- Aspalathus linearis, Cyclopia genistoides, Cyclopia intermedia, Cyclopia subternata, caffeine, detection limit, herbal tea, ions, liquid chromatography, mass spectrometry, reference standards
- Two endemic South African herbal teas, namely rooibos (Aspalathus linearis) and honeybush (Cyclopia spp.), are especially valued for their caffeine-free status. No recent evidence based on state-of-the-art analytical methodology with low limits of detection (e.g. below 1 μg/L) is available. The current study provides such evidence. Randomly selected samples of fermented rooibos (n = 10) and honeybush herbal teas from four species (n = 10 each), namely C. intermedia, C. subternata, C. genistoides and C. longifolia, were analysed and no caffeine detected. Similarly, no caffeine was detected in green rooibos and C. genistoides herbal teas (n = 10 each) indicating that it is absent in the plant. Method specificity was shown to be important since peaks with molecular ion [M+H]+ and product ions resembling those of caffeine were detected, although the retention time and accurate mass did not match those of an authentic reference standard for caffeine.