Fast ultrasound-assisted treatment of inorganic fertilizers for mercury determination by atomic absorption spectrometry and microwave-induced plasma spectrometry with the aid of the cold-vapor technique

This work reports a fast and efficient ultrasound-assisted extraction of mercury in inorganic fertilizers for its determination by cold vapor atomic absorption spectrometry (CV AAS) and microwave-induced plasma optical emission spectrometry (MIP OES), using a 10% (w/v) SnCl2 as reductant agent. A multi-mode sample introduction system (MSIS) was coupled to the MIP OES equipment to make possible the generation of mercury vapor in the nebulizer chamber. The optimized protocol involved the treatment of 150 mg of fertilizer with 4 mL of 30% (v/v) HCl inside glass tubes using a conventional ultrasonic bath for 5 min. Comparable analytical results were obtained for mercury determined by both CV AAS and MIP OES, with better detection limits for the latter technique. The proposed extraction procedure is simple and versatile, and contributes to minimal generation of waste (low volume of diluted HCl) in comparison to the official method.