Inorganic anions profile in the fresh aqueous brews of multiherbal functional products used as vitalizing or slimming drinks

Multiherbal functional products (MFP) are often offered as not exactly defined and controlled blends containing from 6 to 17 different herbal components. MFP is consumed in form of aqueous brews (“herbal teas”) as skin, nail or hair vitalizing agents (UX) and in body weight reducing therapies (OY). Thus, fluoride, chloride, bromide, nitrate, phosphate and sulphate were determined by ion chromatography (IC) in brews of ten UX and ten OY items. IC separation was achieved on the anion-exchange column (250 × 4.0 mm i.d.) within 30 min by isocratic elution using a 3.2 mM Na₂CO₃ as eluent followed by suppressed conductivity detection with detection limit (LOD) in range 0.005 – 0.440 mg/L and 91 – 105% recovery [1,2]. In all set of MFP products (n = 20) the mean content of anions was F^- 22.12; Cl^- 42.26; Br^- 0.85; NO^3- 30.08; PO^4- 65.02; SO₄ ^2- 51.39 mg/L. Compare to the OY products, a significantly increased mean content of anions was observed in the UX agents. The highest content of anions (F^- 47.18; Cl^- 85.52; Br^- 2.22; NO^3- 122.20 PO^4- 111.62; SO₄ ^2- 85.57 mg/L) was determined in the UX5 agent containing such herbal components as pu-erh tea, heartsease, stinging nettle, lemon grass, green tea and yarrow. Minimal content of anions (F^- 19.84; Cl^- 17.26; Br^- 0.56; NO^3- 6.68; PO^4- 39.51; SO₄ ^2- 24.38 mg/L) was observed in the product OY12 with admixture of hibiscus, apple, bitter orange, pu-erh, dandelion, horsetails and grape-fruit peel. Content of Br^- was below LOD of the IC method (0.005 mg/L) in three samples: UX6, OY15, OY20. All obtained IC data were evaluated by multivariate principal component analysis (PCA) which indicates that the UX products have increased total sum of F^-, Cl^- and Br- anions, while OY blends have the increased levels of total sum of PO^4- and SO₄ ^2- anions. PCA of the IC data enabled to differentiate the MFP containing hibiscus and pu-erh tea but not peppermint/yerba mate and green tea. In this way a fraudulent or mislabeled MFP could be recognized.

Acknowledgements: Internal Grant CM-UMK DS-UPB-407/2016-Bydgoszcz, Poland.

Keywords: Functional food, fluoride, anions, ion chromatography, chemometrics.

References:

[1] Bazylak G, Siepak M, Gryn A. Content of some inorganic anions in aqueous brew sof white mulberry leaves used as components of dietary supplements for diabetic subjects. Planta Med 2014; 80: 1476

[2] Michalski R. Simultaneous determination of common inorganic anions in black and herbal tea by suppressed ion chromatography. J Food Quality 2006; 29: 607 – 616