Microwave-assisted green digestion method for a variety of biological samples with hydrogen peroxide as the main digestion solvent

The microwave-assisted digestion method has been widely developed due to its high digestion efficiency and effective avoidance of volatile element loss. However, concentrated strong inorganic acids are still recommended for digestion in the majority of the standards and reported studies. This increases laboratory safety risks and environmental burdens. The present study examines an environmentally friendly, efficient, and safe digestion method for biological samples using hydrogen peroxide (H 2 O 2 ) as the primary digestant. Initially, the concentrations of H 2 O 2 and HNO 3 were optimised, followed by adjusting factors such as pressure, temperature and time to establish a heating programme. Under low-pressure conditions, a digestion solution containing 8%–16% H 2 O 2 and 3%–4% HNO 3 effectively digested various representative animal and plant tissues. This method ultimately achieved a total score of 85 in a comprehensive ecological scale analysis, validating its potential as a green digestion method. Compared with the traditional digestion method, the proposed method produced no visible gas evolution or pungent odor during digestion and yielded a colorless and transparent solution. This study presents a mild and safe digestion method applicable to a variety of biological samples including herbs. It possesses potential application in the pretreatment of samples in medical, food and environmental fields.