Direct solid analysis for the determination of Mn, Ni, Rb and Sr in powdered stimulant plants using high-resolution continuum source atomic absorption spectrometry followed by chemometric classification based on elemental composition, polyphenol content a

In this work, a simple, fast and sensitive method for the determination of Mn, Ni, Rb and Sr in powdered samples of guarana (Paullinia cupana), catuaba (Anemopaegmaglaucum), ginseng (Panax ginseng), ginger (Zingiber officinalis), mate (Ilex paraguariensis) and coffee (Coffea arabica) was developed using direct solid sample analysis and high-resolution continuum source electrothermal atomic absorption spectrometry. The temperature program of the graphite furnace was optimized and the determination was carried out without the use of chemical modifiers. Calibration against a solid reference material was compared to calibration against aqueous standards and no significant differences were observed for Mn, Rb and Sr determination, whereas for Ni the difference in sensitivity was as high as 20%, indicating that calibration using a solid reference material should be adopted. Sixteen samples of stimulant plants from a local market were analyzed for trace elements, total phenolic compounds and antioxidant activity. Trace elemental content ranged from 0.08 μg g− 1(Ni) to 135 μg g− 1 (Mn), total phenolics ranged from 3.37 ± 0.02 to 34.28 ± 0.04 mg GAE g− 1, and antioxidant activity ranged from 1.15 ± 0.65 to 10.32 ± 0.21 TE mmol g− 1. In order to carry out chemometric classification of the plant species, PCA was employed using data from elemental and phenolics contents of the plants, as well as their antioxidant activities. The joint use of these parameters allowed successful distinction between species, showing that these data can be used to discriminate between different stimulant plants.