A new strategy for the isolation and enrichment of sulfonylurea herbicides in grain samples was obtained by using magnetic molecularly imprinted polymers (MMIPs) using carbon nanotubes as the matrix, nicosulfuron as the template molecule, 3-aminopropyltriethoxysilane as the functional monomer, tetraethyl orthosilicate as the cross-linker and cetyl trimethylammonium bromide as the dispersant. The characteristics of the MMIPs were assessed by transmission electron microscopy, vibrating sample magnetometry, X-ray diffractometry, elemental analysis, the Brunauer–Emmett–Teller method and Fourier transform infrared spectroscopy. The binding characteristics of the imprinted materials were researched using isothermal adsorption experiments, kinetics adsorption experiments and selectivity experiments. The recoveries of four sulfonylurea herbicides were more than 80.0% and the detection limits were 0.0107, 0.0151, 0.0147 and 0.0123 μg g⁻¹, respectively. RSDs of intra-day and inter-day precisions in the range of 0.7–2.4% and 5.3–8.4% were obtained, respectively. The results demonstrate that MMIPs are promising for the preconcentration, purification and analysis of sulfonylurea herbicides in grain samples.

A molecularly imprinted polymer (MIP)-matrix solid phase dispersion (MSPD) method for the extraction of camptothecin from Camptotheca acuminate was developed. MIPs were synthesized by a surface imprinting technique using carbon nanotubes as a support, camptothecin as a template, methacrylic acid as a functional monomer, and ethylene glycol dimethacrylate as a crosslinker. The MIPs were characterized by scanning electron microscopy, transmission electron microscopy and Fourier transform-infrared spectroscopy. Isothermal adsorption, dynamic adsorption and selectivity adsorption experiments were also carried out in this study. The MIP-MSPD method coupled with high performance liquid chromatography was applied for the determination of camptothecin in Camptotheca acuminate fruit, bark and leaf. Factors affecting the extraction yield such as the sorbent/sample ratio, dispersion time, and washing and elution solvents were investigated. Under optimized conditions, a good linearity of camptothecin was obtained in a range of 1–200 μg mL⁻¹, and the detection limit of the method was 0.13 μg mL⁻¹. The extraction yields of camptothecin obtained were 0.1055%, 0.0628% and 0.0930% for Camptotheca acuminate fruit, bark and leaf, respectively. The recovery of camptothecin was in the range of 96.1–103.3%. The results showed that this method is fast, selective, cost-effective and environmentally friendly compared with other extraction methods such as stirring extraction, ultrasonic extraction and Soxhlet extraction used for the extraction of camptothecin.

A multifunctional nanocomposite for highly sensitive and rapid detection of tetracycline hydrochloride (TC) has been developed using magnetic quantum dots (MQDs). The thiolated quantum dots (QDs) were conjugated with amino-coated Fe₃O₄ and subjected to crosslinking modification with EDC/NHS through covalent binding. The obtained MQDs were shown to possess superparamagnetic characteristics and fluorescence properties and exhibit a strong orange metal-to-ligand charge transfer emission. The MQDs were characterized by fluorescence spectrophotometry, X-ray powder diffraction, Fourier transform infrared spectroscopy, physical property measurement and transmission electron microscopy. The multifunctional nanomaterial shows excellent fluorescence properties that allow for highly sensitive and short response time for TC detection. Under optimum conditions, a linear calibration plot of the quenched fluorescence intensity at 593 nm against the concentration of TC was observed in the range from 10 to 700 nmol L⁻¹ with a detection limit of 1.2 nmol L⁻¹. The recovery detected with this method was from 95.7% to 99.3% with a relative standard deviation (R.S.D.) below 3%. This method manifested several advantages such as high sensitivity, non-toxicity, short analysis time, low cost and ease of operation.

Micelle-mediated extraction and cloud point preconcentration has been successfully applied to the separation of camptothecin (CPT) fromCamptotheca acuminate.

In this study, we investigated the possibility of reverse micelles which were used for the determination of rhodamine B in lipsticks followed by high performance liquid chromatography (HPLC). The reverse micelle of surfactant sodium 1,4-bis(2-ethylhexoxy)-1,4-dioxobutane-2-sulfonate (AOT) was formed in n-hexane. First, the samples were preprocessed by reverse micelle extraction, and then rhodamine B was extracted from the mixture with methanol by back-extraction. The effects of different parameters including the concentration of surfactant, pH, amount of potassium chloride, ultrasonic time and type of organic solvents were evaluated and optimized during reverse micelle formation. The limit of detection of rhodamine B was 0.01 μg g⁻¹. The intra-day and inter-day precisions expressed as relative standard deviations were 3.6% and 4.5%, respectively. The recovery of rhodamine B obtained was 95.0%. The reverse micelle method proposed for the determination of rhodamine B in real samples of lipsticks has the advantages of simplicity, speed, high precision, low detection limit and the use of inexpensive equipment.