Levels of Selected Metals in Leaves of Cannabis Sativa L. Cultivated in Ethiopia

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Addis Ababa University


Cannabis sativa L. is one of the illicit drug bearing plants. In the present study the levels of essential and non-essential metals in leaves of Cannabis sativa L. were determined in the samples collected from Metema (Amhara Region), Mekelle (Tigray Region), Sheshemene (Oromia Region) and Butajira (South Nations Nationality and Peoples (SNNP) Region). After proper sample pretreatment the volumes of reagents used, digestion temperature and digestion time were optimized and using the optimized conditions the levels of metals were determined by flame atomic absorption spectrometry. The accuracy of the optimized procedure was evaluated by analyzing the digest of the spiked samples with standard solution and varied from 88–103%. The levels of concentration determined (µg/g dry weight) were in the ranges Ca (657–1511), Zn (321–380), Ni (124–172), Cu (122–176), Cd (3–10), Pb (8–10), Cr (4–8). Zn was with the highest concentration from trace metals. A statistical analysis of variance (ANOVA) at 95% confidence level indicated that there is a significant difference in the levels of all metals between the four sample means except Pb. The results indicate that the content of Pb and Cd exceeds the permissible amount for medicinal plants which form the raw materials for the finished products set by World Health Organization (WHO).



Cannabis, Cannabis Sativa L, Trace Metals, Flame Atomic Absorption Spectrometry, Ethiopia