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A rapid and simple preconcentration method using dissolvable Mg/Al layered-double hydroxides (LDHs) and high performance liquid chromatography-photodiode array detection (HPLC-PDA) was developed for the analysis of benzoylurea insecticides (BUs) in water and honey samples. The proposed dissolvable LDHs for the extraction can be prepared in one step by the sequential addition of sodium hydroxide, magnesium chloride, aluminium chloride, and sodium dodecyl sulfate into the sample solution containing the target BUs. The co-precipitate phase was simply obtained after centrifugation, and the phase was then dissolved with formic acid before analysis by HPLC. The developed method provided an enrichment factor of 12.5-23.7. LODs were obtained in the range of 0.1-0.3 μg L-1 for deionized water, 0.2-2.0 μg L-1 for environmental waters, and 0.5-2.0 μg L-1 for the analyzed honey samples. Good recoveries ranging from 78.4 to 117.8% and 72.7 to 117.9% for water and honey samples, respectively, were obtained.

Herein, a novel, fusiform-like magnetic metal–organic framework material (Fe3O4-NH2@MOF-235) was fabricated by a facile two-step solvothermal approach. Then, Fe3O4-NH2@MOF-235 was applied as an adsorbent in magnetic solid-phase extraction (MSPE) coupled with high-performance liquid chromatography (HPLC) for the simultaneous extraction and determination of five kinds of benzoylurea insecticides (flufenoxuron, chlorbenzuron, teflubenzuron, diflubenzuron and triflumuron) from honey, fruit juice and tap water samples. Moreover, potential variables influencing the MSPE efficiency were optimized. Under the optimized conditions, an excellent linearity was achieved in the range of 1.0–300.0 μg L−1 for teflubenzuron and flufenoxuron and 2.0–300.0 μg L−1 for diflubenzuron, chlorbenzuron and triflumuron, with the correlation coefficients of 0.9991–0.9995. The limits of detection for the analytes were 0.25–0.5 μg L−1, and the recoveries at three fortified concentration levels ranged from 76.45% to 90.74% for the honey samples, 79.95–95.27% for the fruit juice samples, and 84.02–99.62% for the tap water samples. The π–π stacking and hydrophobic interactions between Fe3O4-NH2@MOF-235 and the analytes played an important role in the adsorption process. Moreover, maximum adsorption could be achieved within 5 minutes with very little adsorbent for all the samples. Therefore, the magnetic Fe3O4-NH2@MOF-235 composite combined with MSPE is a convenient approach to detect benzoylurea insecticides in actual samples.

A pretreatment method using hyperbranched polyester (HBPE) composite as sorbent based on dispersive micro-solid-phase (d-μ-SPE) extraction preceding high-performance liquid chromatography analysis was developed for the determination of benzoylurea insecticides (BUs) in water samples. Parameters that may influence the extraction efficiency, such as the diameter and the amount of the sorbent, extraction and desorption time and the pH value of the solution, were investigated and optimized using batch and column procedures. Under optimized conditions, good linearity was obtained for all of the tested compounds, with r values of at least 0.9924. The linearity of the method was determined in the range of 1–25 000 μg L−1. The limits of detection (LODs) ranged from 0.024 to 0.068 μg L−1. The recoveries of the four benzoylurea insecticides in water samples increased from 85.50–96.12%. The results confirmed the possibility of using hyperbranched polyester in the determination of relatively hydrophobic trace pesticides residues. Finally, the proposed method was applied to the determination of BUs in water samples with satisfactory results.

A novel and simple ionic-liquid-mingled air-assisted liquid–liquid microextraction based on solidification of floating organic droplets combined with high performance liquid chromatography was developed for the determination of six benzoylureas (BUs) in water and honey samples. In this method, a mixture of low-density and low melting point extraction solvents and aqueous sample solutions was rapidly sucked up and injected several times using a glass syringe. The influence of the main factors on the efficiency of this procedure is studied. Under the optimal conditions, the enrichment factors (EFs) for BUs were acquired in the range of 144 to 187, limits of detection (LODs) were between 0.01 and 0.1 μg L−1 and limits of quantitation (LOQs) were changed in the range of 0.03 and 0.33 μg L−1. The obtained extraction recoveries ranged from 84.03% to 109.20% with intra-day lower than 4.5%, and inter-day precision lower than 6.5%. The method is successfully applied to determine the BUs in environmental water and honey samples with recoveries in the range of 78.57–109.72%, which proved the potential use of this method in real samples.

A rapid, easy to operate, and sensitive method was developed for the trace determination of benzoylurea insecticides based on a micro-solid phase extraction with highly ordered TiO2 nanotube arrays as the adsorbent prior to high performance liquid chromatography. The experimental results indicated that a good linear relationship was achieved between the peak areas and the concentrations of benzoylurea insecticides in the range of 0.1–40 μg L−1. The limits of detection (LODs) of diflubenzuron, chlorbenzuron, triflumuron and chlorfluazuron were 0.082, 0.026, 0.049 and 0.076 μg L−1, respectively. The proposed method was successfully used to determine the benzoylurea insecticides in environmental water samples. The spiked recoveries in the range of 76.5–102.4% were achieved. All these results demonstrated that the proposed method was of great value and would have great potential in the enrichment and determination of trace pollutants in the future.

Rapid and high yielding synthesis of medium ring lactams was made possible through the use of a benzoylurea auxiliary that serves to stabilize a cisoid amide conformation, facilitating cyclization. The auxiliary is released after activation under the mild conditions required to deprotect a primary amine, such as acidolysis of a Boc group in the examples given here. This methodology is a promising tool for the synthesis of medium ring lactams, macrocyclic natural products and peptides.