Microwave-assisted extraction of trace metals from sediments using dilute hydrogen peroxide and dilute nitric acid prior to their determination by inductively couple plasma-optical emission spectrometry

Background and Objectives: Contamination of aquatic sediments by trace metals is one of the global problems. This is because trace metals in sediments are persistent and nonbiodegradable. They may pose danger to flora and fauna since they can be released into freshwater systems. This study aimed at the development of microwave-assisted extraction using diluted hydrogen peroxide and nitric acid for extraction of trace elements from sediment samples prior to inductively coupled plasma optical emission spectrometry (ICP OES) determination. Methods: Response surface methodology (RSM) based on the Box-Behnken design was used for the optimization of factors affecting the microwave-assisted extraction process. The optimum conditions, for quantitative extraction of trace metals such as Cd²⁺, Cu²⁺, Cr²⁺, Pb²⁺ and Zn²⁺ were 16 min, 1.5 mol L^-1 and 15% for extraction time, nitric acid concentration and H₂O₂ concentration, respectively. Results and Discussion: Under optimized conditions, the accuracy of the method was evaluated by analyzing loamy clay certified reference materials (CRM052) and the recoveries were above 92%, suggesting that the obtained results were in good agreement with the certified values. The developed method has shown reproducibility (RSD < 5%), as well as relative low limits of detection (0.02-0.09 µg g^-1) and limit of quantitation (0.07-0.3 µg g^-1). The developed analytical method was applied for extraction and the determination of trace metals in freshwater sediment samples. Conclusion: The method displayed advantages such as simplicity, rapidity, environmentally friendly and safe compared to classical methods that are based on concentrated acids.