Analysis of inorganic chemical constituents in the secretions of Populus euphratica

Populus euphratica (P. euphratica) is a key desert riparian plant species in central Asia. This species has adapted to harsh habitat conditions by excreting salts in the form of P. euphratica secretion (PES). PES is known to have therapeutic benefits for ailments such as sore throats, gastrointestinal disorders, and neurasthenia. Meanwhile, local inhabitants harvest PES for the preparation of an alkaline paste, a digestive beverage for their diet and flour leavening agent. Despite its various uses, the chemical composition of PES remains to be elucidated. In this study, the elemental and ionic composition of PES was quantitatively analyzed using elemental analysis, ICP-OES, ion chromatography, and potentiometric titration. The main inorganic compounds were determined by X-ray diffraction. Na, K, Ca, Mg, Cl⁻, HCO₃⁻ and SO₄²⁻ were identified in PES. Na₂CO₃·NaHCO₃·2H₂O (Trona) and KCl, the two main components, were found and quantified in PES for the first time. Additionally, NaHCO₃, NaCl and SiO₂ were also detected in PES. This work thoroughly characterized PES, a highly nutritious and culturally valued food material, through qualitative and quantitative analyses, fully elucidating its inorganic chemical composition. These findings address several gaps in the fundamental composition data of PES and support its physiological functions in plants and potential health benefits in traditional applications.