A simple, low cost, and green method was developed for the synthesis of water-soluble and well-dispersed fluorescent carbon nanodots (CDs) via a one-step hydrothermal treatment of potatoes. The as-prepared CDs exhibit a strong blue fluorescence, with a quantum yield of up to 15%. We further explored the use of these CDs as a novel sensing probe for the label-free, sensitive and selective detection of Fe³⁺. This is based on strong fluorescence quenching due to the complex formed between the CDs and Fe³⁺. The detection limit was as low as 0.025 μmol L⁻¹, and different concentrations corresponded to different sensitivities. The linear ranges were 1.0–5.0 μmol L⁻¹ and 5.0–50.0 μmol L⁻¹ at lower and higher concentration ranges respectively, and the recoveries of the spiked water samples were 93.7–101.5%. Therefore, the as-prepared CDs could meet the requirements for the monitoring of Fe³⁺ in environmental samples.

CdSe quantum dots (QDs) have traditionally been synthesized in organic phase and then transferred to aqueous solution by functionalizing their surface with silica, polymers, short-chain thiol ligands, or phospholipid micelles. However, a drastic increase in the hydrodynamic size and biotoxicity of QDs may hinder their biomedical applications. In this paper, the TGA-capped CdSe QDs are directly synthesized in aqueous phase at freezing temperature, and they prove to possess high QY (up to 14%).

A microwave-assisted extraction approach based on ionic liquids of different chain lengths was successfully applied to the extraction of ten flavonoid glycosides from the flowering heads of Chrysanthemum morifolium Ramat. The pretreated sample was quantified by HPLC-ESI-MSⁿ. The main components were identified as flavonoid glycosides, including three luteolin glycosides, three apigenin glycosides, three kaempferide glycosides, and one acacetin glycoside according to the characteristics of the corresponding CID mass spectrometric patterns. Eight ionic liquids from the imidazolium family with different chain lengths, namely, 1-alkyl-3-methylimidazolium bromide, [C_nmim]Br, (n = 2–16) were studied as extraction medium in water. Results indicated that alkyl chain length had an irregular impact on the extraction efficiency. Moreover, the best extraction efficiency was achieved by 1-dodecyl-3-methylimidazolium bromide aqueous solution ([C₁₂mim]Br). Besides the alkyl chain length of the cations, other factors influencing extraction efficiency were systematically investigated, including concentration of the IL solutions, extraction time, matrix-to-solvent ratio and irradiation power.