The analysis of the essential metal contents in khat (Catha edulis Forsk) from Meru County, Kenya

Abstract

Background

Chemical composition of plants has attracted considerable interest in recent years with considerable research tailored into determining metal contents in food substances. Particularly, essential elements which are necessary for normal human body functioning and are strongly recommended in optimal proportions for better health. This study determined the levels of essential elements; calcium (Ca), magnesium (Mg), sodium (Na), potassium (K) and manganese (Mn) in eleven khat (Catha edulis Forsk) samples collected from Meru County.

Methodology

1.0 g of dry ground khat samples were wet-digested in a solvent mixture of 10 mL of HCl, HNO₃ and 20 vol of H₂O₂ for 3 h at variable temperature of 50–90 °C and later reconstituted in 25 mL 0.05 $\text{mol}{L}^{-1}$ HCl before analysis. The samples were analyzed using inductively coupled plasma atomic emission spectrometry (ICP AES) after acid digestion whereas Hierarchical cluster analysis (HCA) and principal component analysis (PCA) were used to investigate elemental characteristics and determine the sources of essential metals in khat. In addition, Pearson correlation coefficient (PCC) was used to evaluate the relationships between the essential metals.

Results

Spinach leaves certified reference material (CRM 1750a) was analyzed and the percentage recoveries (%) of 98.4 and 101.7 determined showing that the digestion method employed in this work had adequate accuracy. The validated method was employed for the analysis of all the khat samples. The analyzed metal concentration ranges ($\text{mg}100g^{-1}$) in fresh-weight basis per day of five metals were 160.9–267.3, 44.6–81.7, 2.0–3.0, 237.6–393.6, and 220.3 -349.0 for Ca, Mg, Mn, K, and Na, respectively. Both HCA and PCA results showed that these elements could be linked to natural soils and anthropogenic sources. PCC reported significant correlations between Na and K indicating they may have been derived from the same source. The daily metal intakes were below the World Health Organization (WHO) permissible limits implying no associated health risks for khat users.

Conclusion

Based on the findings of this study, the consumption of khat from regions of Meru County may be a potential source for essential elements required for human biological processes.