Ultrasound-assisted pretreatment of solid samples in the context of green analytical chemistry

Sample preparation has witnessed transformation in recent years, with the main efforts focused on acceleration, simplification, miniaturization and automation of the operations involved. Ultrasound is a clean, efficient energy that has dramatically improved many sample-preparation protocols. The unique conditions provided by acoustic cavitation have enhanced solid-sample pretreatments (e.g., digestion, dissolution and extraction), which are typically applied prior to detection.At present, awareness of green aspects has led many analytical chemists to consider key indicators (e.g., operation time, safety, volume/concentration of solvents and energy consumption) when developing new sample-preparation methods. This overview tackles the main applications of ultrasound for pretreatment of solid samples and some liquid samples with a complex matrix (e.g., wastewater) in the context of green analytical chemistry.

► We revise ultrasound-assisted solid sample pretreatment for trace analysis.
► Green issues of ultrasound energy are emphasized.
► Processes such as digestion, extraction, solubilisation and slurry formation are discussed.
► We provide relevant applications of ultrasound under the perspective of Green Analytical Chemistry.