Determination of trace metal concentrations in different parts of the khat varieties (Catha edulis) using inductively coupled plasma-mass spectroscopy technique and their human exposure assessment

Background: Khat (Catha edulis, family: Celastraceae) is a plant that is native to Africa and Arab peninsula and is used for their amphetamine-like properties. Although the use of Khat is banned in Saudi Arabia, people particularly in southern Jazan province manage to get it from Yemen, and the use is increasing steadily. Objective: Five most commonly used varieties of Khat namely Gaifi, Kofat, Jahasha, Faqarah Menjed, and Faqarah Aswad were selected for the study. Materials and Methods: Metal ion concentrations were determined using inductively coupled plasma-mass spectroscopy. Since Khat is available as one bundle consisting of three parts of the plant, metal ions in all three parts were determined separately for comparison purpose. The concentrations (mg/kg) of 20 metal ions were determined in Nwaif leaves (new and smaller in size), Gafra leaves (old and larger in size), and stem of the plant and compared with the Provisional Tolerable Weekly Intake (PTWI) and acceptable daily intake (ADI) of metal ions to study the health hazards posed by them. Results: The non-essential metal ion Strontium (Sr) was present in highest abundance in all the samples with a concentration range of 498.6 ± 18.9–3837 ± 52.1 mg/kg followed by Copper (215.4 ± 12.3–3054 ± 45.2 mg/kg), Zinc (23.17 ± 0.4–1490 ± 32.6 mg/kg), and Manganese (108 ± 5.8–1357 ± 18.6 mg/kg). Several toxic heavy metal ions including Arsenic, Lead, and Cadmium were also present in trace concentrations in many samples. Conclusion: Many metal ions were observed to be present in concentrations much higher than their PTWI and ADI which further allude to the extremely hazardous nature of Khat plants. Multicomponent variate analyses were also performed using chemometric methods to establish the possible correlation between samples.