Quantitative analysis of some oligo-elements and heavy metals in some species of Thymus from Morocco

In order to valorise natural substances, concentrations of 20 mineral elements were evaluated in five species of Moroccan thyme. These species which belong to the Lamiaceae family are Thymus leptobotrys, Thymus broussonetii, Thymus maroccanus, Thymus pallidus and Thymus satureioïdes growing in different regions of central and southern Morocco. Samples of plants were subjected to digestion and heavy metals were determined by inductively coupled plasma mass spectrometry. The highest concentrations of calcium, iron, zinc, cobalt and chromium were registered in T. broussonetii, T. pallidus, T. leptobotrys, T. maroccanus and T. satureioïdes with respective values of 1991, 423, 73, 6 and 11 mg/kg. Furthermore, silicium and boron were analysed only for the species T. broussonetii and their respective concentrations were found to be 112 and 43 mg/kg. The ultra trace elements Si, B, Ni, Ni, As, Li, V and toxic elements Cd and Pb were also evaluated. The results were treated by the method of principal components analysis.