Analysis of Indian mint (Mentha spicata) for essential, trace and toxic elements and its antioxidant behaviour

Mint, belonging to the genus Mentha in the family Labiatae (Lamiaceae) is pungent in taste with post digestive effects and hot potency. Ten samples of mint leaves, collected from four different locations in North-West parts of India (Roorkee, Dehradun, Baghpat and Uttarkashi) were analysed for seven minor (Al, Na, K, Ca, Cl, Mg, and P) and 20 trace (As, Au, Ba, Br, Co, Cr, Cs, Eu, Fe, Hf, Hg, La, Mn, Rb, Sb, Sc, Se, Sn, Th and Zn) elements by instrumental neutron activation analysis (INAA). Also Ni, Cu and Cd were determined by atomic absorption spectrophotometry (AAS). Samples along with reference materials (RMs) and synthetic primary standard were irradiated at ∼1013 n cm−2 s−1 and its γ-activity was measured using HPGe detector and MCA system. Most elements were found in widely varying amounts depending on the location, e.g. Na (0.21–0.86 mg/g), K (12.4–53.3 mg/g) and Ca (5.82–16.8 mg/g) whereas mean contents of other nutrient elements in mint were: Fe (108 ± 22 μg/g), Mg (4.83 ± 0.92 mg/g), Mn (53.5 ± 9.6 μg/g), P (3.88 ± 0.94 mg/g), Cu (16.9 ± 1.8 μg/g), Zn (21.0 ± 4.7 μg/g) and Se (0.18 ± 0.03 μg/g). Further, DPPH free radical scavenging activity test in diethyl ether extract showed 100% activity at ∼40 μg/L suggesting it to be antioxidant in accordance with literature reports.