Quantitative detection of gold nanoparticles in soil and sediment

Ever-growing application of engineering nanoparticles in many sectors of the society requires efficient methods to extract them from soil and sediment, for the sake of environmental protection. In this study, we develop a new method which uses sodium pyrophosphate solution (TSPP, Na₄P₂O₇) as extratant to extract gold nanoparticle (AuNPs) from soil and sediment under optimized parameters through vortexing, water bath oscillation, ultrasonic bath and precipitation. SP-ICP-MS was used for the detection of number concentration, mass concentration and size distribution of AuNPs in soil. UV irradiation was innovatively used to directly degrade soil organic matter to improve the recovery of AuNPs due to their low recovery rate in rich organic soils. It could be found that the mass fraction recovery increased from 36% (without UV digestion) to 83% (with 48h UV digestion). The extraction method is versatile for different coating layers and wide-ranging particle sizes in real soil and sediment. Therefore, the rapid and efficient characterization and quantification of AuNPs in soil and sediment are achieved, and the researches on the extraction method of AuNPs and their behavior and toxicity assessment in soil environment can be enriched.