Sodium(I)-doped graphitic carbon nitride with appropriate interlayer distance as a highly selective sorbent for strontium(II) prior to its determination by ICP-OES

A novel extraction protocol of nano-polystyrene from biological samples

Toxicological data demonstrate that nanoplastics (NPs) can cause direct adverse health effects. However, a method for quantifying NPs in biological samples is lacking to date. In this study, a diatomite associated coagulation-sedimentation extraction (CSE) protocol was developed to selectively enrich polystyrene nanoplastics (PS-NP) from microplastics (PS-MP) in the digest of animal tissues, which were then analyzed using pyrolysis gas chromatography-mass spectrometry. We demonstrate that 0.02 g of 7-μm diatomite can selectively adsorb 70-nm PS-NP in 5 mL oyster digest. The method works in the range of 0.006-5 μg PS-NP per 0.5 g wet weight tissue, which has been verified via samples of environmentally contaminated oysters and chow diet PS-NP-treated C57BL/6 mice (digestive tract, kidney, and liver tissues). The particle size-dependent colloidization or buoyancy theoretically supported the general CSE procedure. This work will pave the way for assessing human exposure to NPs and associated health risks.

Magnetic N-rich carbon nitride framework material for the high selectivity extraction and determination of La(III)

A novel magnetic C₃N₅ framework material (Fe₃O₄/C₃N₅) was developed as a high selectivity extractant for La(III) determination in food samples. The Fe₃O₄/C₃N₅ material was synthesized by thermal deammoniation method and has larger surface area (100.3 m² g^-1) and more effective adsorption sites compared with that of individual C₃N₅ material (19.4 m² g^-1). It was proved that Fe₃O₄/C₃N₅ material displayed excellent selectivity and adsorption capacity for La(III). In addition, adsorption isotherm and kinetic data indicated that La(III) adsorption based on Fe₃O₄/C₃N₅ material is a monolayer adsorption which is compatible with Langmuir model and follows a pseudo-second-order kinetic equation. By using Fe₃O₄/C₃N₅ material as extractant, an analytical method was established with low limits of detection (3σ, n = 6) of 10.4 μg L^-1, reasonable recoveries ranged from 86% to 106% and good precision with the RSD less than 10.7%. The analytical method was further applied to the determination of trace La(III) in food sample. It evinced that the concentration of La(III) in sea fish is 13.2 μg kg^-1 and the content of ¹³⁸La is 0.138 μg kg^-1, which is 1.03% of total La(III).