A Green Digestion Method Based on Deep Eutectic Solvent for Determination of Essential Trace Elements in Blood Serum Samples of Tuberculosis Children

Background Tuberculosis is spreading throughout the globe, and it is a main cause of death especially children in developing countries. Disturbances in the concentrations of essential trace elements are associated with impaired immunity in pulmonary tuberculosis infection. Objective In this study, the alterations in concentrations of essential trace elements, copper (Cu), iron (Fe), and zinc (Zn) in biological sample (blood serum) were determined in children with pulmonary tuberculosis (PTB), age 5 to 10 years, before and after a 6-month anti-tuberculosis treatment period. Methods An environmentally friendly methodology was used to treat the serum sample by means of a deep eutectic solvent, composed of oxalic acid and choline chloride (Ox-ChCl) at diverse molar ratios, and then shaking the sample mixture was sonicated in ultrasonic bath at different temperatures (40-85°C). Subsequently, dilute HNO3 (0.5 M) was added and tubes centrifuged. The supernatant solution was subjected to inductively coupled emission plasma spectrophotometry. The effects of various factors on the efficiency of digestion of the serum samples to determine Cu, Fe, and Zn, including volume of deep eutectic solvent and its mole ratio, temperature and shaking time of ultrasonic bath (sonication time) were checked. Results The data indicate that the PTB patients have a changed profile of all three metals in their sera and this could be more due to the active disease rather than underlying deficiencies. Compared with the non-diseased children, the levels of Fe and Zn in the serum samples of PTB-affected children were considerably lower (P Conclusion After 6-month treatment, the levels of Fe and Zn were enhanced about 16% and 30%, respectively, while 23% Cu was decreased in serum samples of PTB children. These values were slightly lower than reference values. Highlights Disturbances of essential trace elements levels are associated with impaired immunity. A deep eutectic solvent, composed of choline chloride and oxalic acid, was used for digestion of serum. The levels of Fe and Zn in the serum samples of PTB-affected children were significantly lower (P < 0.05). Negative correlations of Zn and Fe with Cu in serum samples of PTB-infected children were observed.