Investigation of heavy metal accumulation in mung bean (Vigna radiate) through inductively coupled plasma optical emission spectroscopy

Abstract

Although mung bean is cultivated for its nutritional crop in a different region of Ethiopia through irrigation, its production is hindered by excess accumulation of heavy metals in the environment. The presence of excess heavy metals in the environment subsequently leads to the contamination of consumable products, hampered crop productivity, and subsequently affects human health. The present study aimed to determine the concentrations of selected heavy metals (Pb, Cu, and Cr) in the mung bean collected from Shewarobit, Northcentral, Ethiopia, using inductively coupled plasma optical emission spectroscopy (ICP-OES). Dried seeds of mungbean were digested in a microwave oven by nitric acid and hydrogen peroxide for 1hr at a temperature of 90°C to 95 °C by a hot plate digester and then the concentration of Pb, Cu, and Cr was measured through inductively coupled plasma optical emission spectrophotometry (ICP-OES). The result revealed that the concentration of heavy metals in the samples was 2.51 mg/L, 6.53 mg/L, and 0.38 mg/L for Pb, Cu, and Cr, respectively. Copper (Cu) was found to be higher, followed by lead (Pb) and chromium (Cr). The overall accuracy and applicability of the method were confirmed through spiking experiments (recovery) in the range of 80 to 120%, which account for 110.5% ± 0.039, 96.0% ± 0.236, 102.0% ± 0.085 for Pb, Cr, and Cu, respectively. The concentration of Cu and Cr in mung bean falls under the permissible limit. However, the amount of lead is higher than the permissible limit and it is unsafe to consume. Thus, appropriate measures should be done to adjust its concentration.