Optimization of Ultrasound-Assisted Extraction of Essential and Non-essential/Toxic Trace Metals in Vegetables and Their Determination by FAAS and ICP-OES: an Evaluation of Human Health Risk

Vegetables are significant edible crops, and human beings are dependent upon them as a diet for their survival, and uptake of metals through vegetable roots can be piled up at higher levels in their comestible parts which can cause harmful effects upon human health. The present study aimed to determine the composition of essential (Mn, Fe, Cu, and Zn) and non-essential/toxic trace (Al, Cr, As, Cd, and Pb) metals in the edible parts of some common vegetables (carrot, reddish, cauliflower, pumpkin, and spinach) by FAAS and ICP-OES. A simple and fast ultrasound-assisted extraction (UAE) procedure combined with dilute acids was developed. The extraction condition adequate to obtain the maximum response was a pre-sonication time of 5 min, 6 min of sonication time at 90 % sonication amplitude, 60 °C temperature, and 5.0 mL of HNO 3 (0.5 M)-H 2 O 2 (10 %) for 500 mg sample. Certified reference materials (NIST 1515 and NIST 1570a) were also analyzed for accuracy studies in terms of % recovery which were obtained in range between 96.0 and 108.3 %, while the precision was performed in repeatability (n = 10) study, yielding % RSD ≤ 2.61. The proposed UAE procedure was the efficient, reliable, and valid alternative to conventional acid digestion method, with the advantage of short analysis time and less consumption of reagents for sample preparation. As far as the concern of human health risk assessment, THQ value for Cd in all vegetables is ≥ 1 which indicated the Cd ingested with vegetables suggesting that the consumers may be facing health risk, especially the children are more vulnerable, whereas CR value of Cr for cauliflower, pumpkin, and spinach obtained ranged between 3.5 and 9.5 × 10 −3 posed a slight threat to carcinogenic health risk.