Assessment of molecular dynamics in natural Shilajit using low-field NMR relaxometry for geographical traceability

Abstract Shilajit (Mumijo) is a phytomineral exudate known for its therapeutic potential, traditionally used in Ayurvedic medicine. Its molecular composition and consequently its therapeutic properties are influenced by geographical origin. Low-field nuclear magnetic resonance (LF NMR) offers a non-destructive tool to assess the molecular behavior of Shilajit rapidly and non-destructively. Twelve raw Shilajit samples from five regions (Iran, India, Nepal, Russia, and Kyrgyzstan) were analyzed using LF NMR at 15 MHz. Longitudinal magnetization relaxation ( T 1 ) and transverse magnetization relaxation ( T 2 ) relaxation times were measured using an inversion-recovery and Carr–Purcell–Meiboom–Gill pulse sequence, respectively. Three distinct relaxation behavior groups were identified. Group I showed only T 1 (solid samples with undetectable T 2 ), group II exhibited single T 1 and T 2 (moderately viscous, hydrated samples), while group III revealed biphasic T 2 relaxation (indicating proton heterogeneity). Clear differences in relaxation profiles were observed across geographical origins, with Iranian samples showing the widest range of T 1 values, while Russian and some Iranian samples exhibited dual T 2 components. LF NMR relaxation parameters ( T 1 , T 2 ) are strongly dependent on the geographic origin and molecular structure of Shilajit. The technique shows promise for use in authentication and traceability of Shilajit, enabling differentiation based on relaxation signatures.