Electromembrane extraction of clenbuterol from swine urine for monitoring illegal use in livestock.

The illegal use of clenbuterol seriously endangers food safety and human health. Accurate monitoring of the illegal use of clenbuterol in livestock can efficiently prevent the clenbuterol residue pork products from entering the consumer market. Thus, in this study, a simple, rapid, and sensitive method for the determination of clenbuterol in swine urine was developed using electromembrane extraction combined with liquid chromatography-tandem mass spectrometry. It should be noted that the electromembrane extraction method presented many advantages of simple operation, fast mass transfer rate, good sample clean-up capability, and less organic solvent consumption. The effect of important factors on the extraction efficiency of clenbuterol was investigated. Under the optimal conditions, good linearity was achieved for clenbuterol over the range of 1-1000 ng/ml (linear correlation [R2 ] = 0.9996). The recoveries of clenbuterol in swine urine at three spiked levels ranged from 83.7% to 110.0% with relative standard deviation values lower than 9.7% (n = 4). The limits of detection and quantification for clenbuterol were 0.07 and 0.25 ng/ml, respectively. These results suggested that the proposed method has great potential for the extraction and determination of trace analyte in a complex sample matrix for monitoring illegal use in livestock.

Electromembrane extraction of nicotine in inhaled aerosols from tobacco cigarettes, electronic cigarettes, and heated tobacco products.

Heated tobacco products and electronic cigarettes are considered as alternatives to traditional tobacco cigarettes. However, it is crucial to monitor and compare the nicotine concentration in inhaled aerosols from these tobacco products, owing to the addictive nature and adverse effects of nicotine on human health. This study aimed to provide an electromembrane extraction (EME) combined liquid chromatography method to extract and determine nicotine in different inhaled aerosols. EME showed high extraction efficiency, selectivity, and sample clean-up capability. Under the optimal parameters, the linear range for nicotine was 0.1-200 mg L-1 (r2 > 0.9998), and the limit of detection was 0.02 mg L-1. Good precision was obtained with the intra- and inter-day relative standard deviations of 2.2 % and 2.8 %, respectively. Repeatability was satisfactory (<7.7 %), and recoveries ranged from 81.0 % to 112.8 %. Finally, this method has been successfully used for the determination and comparison of nicotine in aerosols from these three tobacco products.

Determination of ractopamine residue in animal derived foods using electromembrane extraction followed by liquid chromatography tandem mass spectrometry.

A simple, sensitive and accurate analysis method based on electromembrane extraction (EME) and liquid chromatography tandem mass spectrometry (LC-MS/MS) was developed for the extraction and determination of ractopamine residue in animal derived foods for the first time. Several parameters that affecting the extraction efficiency of EME were optimized, including the type of supported liquid membrane (SLM), chemical composition of acceptor solution, extraction voltage and extraction time. Under the optimum conditions, the developed EME-LC-MS/MS method obtained a wide linear range (1-1000 ng/g), low limit of detection (0.07-0.11 ng/g), satisfactory recoveries of 80.3-108.8%, and high precision (5.5-7.9%). The developed method showed advantages of green, fast mass transfer rate, excellent clean-up ability, high accuracy and high sensitivity, which demonstrated its great potential for monitoring the illegal use of hazardous substances in foods.

Selective extraction and determination of steroidal glycoalkaloids in potato tissues by electromembrane extraction combined with LC-MS/MS.

For the first time, electromembrane extraction (EME) combined LC-MS/MS was applied to extract and determine α-solanine and α-chaconine in different potato tissues using NPOE containing 20% (v/v) DEHP as supported liquid membrane (SLM). Under the optimal conditions, the proposed EME-LC-MS/MS method was evaluated using spiked fresh potato peel sample. The linear range for α-solanine and α-chaconine was 5-1000 ng mL-1 (R2 > 0.9991), with LOD and LOQ of 1.2-1.5 ng mL-1 and 4.1-5.2 ng mL-1, respectively. Repeatability for α-solanine and α-chaconine at three concentration levels was satisfactory (<4.9%), and recoveries ranged from 73% to 106%. Finally, the EME-LC-MS/MS method has been successfully employed to determine α-solanine and α-chaconine in sprouted potato peel and tuber samples, indicating that EME exhibited high selectivity and efficient sample clean-up capability. Consequently, EME showed great potential for extraction and purification of toxic and bioactive basic compounds from complex plant tissues.

Metal-Organic Gel-Modulated Synthesis of Hierarchically Porous Molecularly Imprinted Polymers for Efficient Removal of Sildenafil from Water.

Molecularly imprinted polymers (MIPs) with high specific recognition capability are promising in environmental remediation. However, traditional MIPs usually show poor specific binding affinity toward templates in pure aqueous medium, thus greatly limiting their practical applications in wastewater treatment. Herein, we proposed a facile and versatile method to synthesize a water-compatible hierarchically porous MIP (HP-MIP), in which a metal-organic gel (MOG) was formed by in situ assembly and acted as a removable structural modulator. Remarkably, the integration of the MOG modulator and template imprinting defects significantly improved the specific template binding affinity of HP-MIP in water. The adsorption behavior of HP-MIP fitted well with the heterogeneous Freundlich isotherm, suggesting that HP-MIP possessed greater site heterogeneity to sildenafil than HP-NIP, which confirmed the efficiency of HP-MIP for the removal of sildenafil from water. This approach provides an important pathway to prepare water-compatible porous MIP for efficient removal of highly toxic organic pollutants from wastewater.

Liquid-Phase Microextraction or Electromembrane Extraction?

Isolation of substances by liquid-phase microextraction (LPME) or electromembrane extraction (EME) is becoming more and more important in analytical chemistry. However, the understanding of the mass transfer in LPME and EME is limited, especially for highly concentrated samples. In this work, the mass transfer in LPME and EME from aqueous samples (0.5-200 mg L-1) was studied in terms of recovery, equilibrium time, flux, and mass transfer capacity. In both EME and LPME, high recoveries were achieved at low analyte concentration, and the recoveries decreased at high analyte concentration. For EME, the loss in recovery was partly compensated by increasing the extraction voltage (from 50 to 200 V), while the LPME recovery at high analyte concentration was improved by increasing the extraction time (from 30 to 180 min). EME was superior in terms of equilibrium time and flux, while LPME provided much higher mass transfer capacity especially for highly concentrated samples. Moreover, the recovery was much more sensitive to high analyte concentrations in EME than in LPME, and the EME recovery decreased significantly above 50 mg L-1, indicating that LPME could be used to isolate analytes in a wider concentration range than EME. We believe that this fundamental study will be of great importance for the selection of a suitable membrane-based microextraction technique.

Hybrid breath figure method: A new insight in Petri dishes for cell culture.

The traditional Petri dish, which has not been changed in almost 60 years, has clear limitations when it is applied to cell cultures in a modern biological laboratory. In this work, by integrating the advantages of both the semidirect breath figure (sDBF) method and the traditional breath figure (BF) method, we proposed for the first time a novel hybrid BF method for the fabrication of honeycomb-patterned Petri dishes with mPEG self-assembly in the pores. Due to the amphiphilic structure of mPEG, the active OH groups of mPEG were located inside the pores of the dishes, which could covalently couple with other functional materials. For instance, in this work, an antibacterial agent was immobilized onto the dish surface via a typical coupling reaction. Because of the size difference between the bacteria and cells, the prepared dishes had selective antibacterial activity but noncytotoxicity against mammalian cells. The present hybrid BF method provides a new insight for endowing commercial PS Petri dishes or other membranes with special topographical structures and functions, which could solve the long-term challenges of cell cultures in the future.