Combination of sonication and heating for metal extraction from inorganic fertilizers prior to microwave-induced plasma spectrometry determinations

This work reports a fast and efficient method for metal extraction in inorganic fertilizers by combining heating and sonication using an ultrasonic bath. Microwave-induced plasma optical emission spectrometry (MIP OES) was applied for the determination of Cd, Cu, Cr, Mn, Pb, and Zn in the extracts. Higher efficiency of metal extraction (∼100% for all metals except to Cd) was obtained for the treatment of 150 mg of fertilizer with 4 mL of 50% (v/v) HCl sonicated for 10 min and heating at 85 °C. Extractions applying only heating did not provide satisfactory results. The proposed procedure is simple and contributes to reduced production of waste in comparison to the official method.