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.

Determination of hydroxypolycyclic aromatic hydrocarbons in urine by electromembrane extraction coupled with liquid chromatography.

Polycyclic aromatic hydrocarbons (PAHs) have been classified as the earliest discovered class of environmental carcinogens, seriously endangering human health and ecological safety, and the hydroxylpolycyclic aromatic hydrocarbons (OH-PAHs) in human urine are considered as the main biomarkers to evaluate the exposure levels of PAHs in human body. Therefore, it is necessary to develop an accurate and sensitive method for the determination of urinary OH-PAHs. Herein, we proposed electromembrane extraction (EME) as a simple, effective and ecofriendly sample pretreatment technique for selective extraction, purification and enrichment of four typical OH-PAHs (2-naphthol, 2- and 3-phenanthrol, 2-hydroxyfluorene) in human urine for the first time. Under the optimum conditions, an analytical method of EME coupled with HPLC was established, which provided wide linear ranges for four OH-PAHs from 1 to 500 ng mL-1 with low LODs of 0.05-0.3 ng mL-1. The average recoveries of four OH-PAHs at three spiked levels in human urine were 81.6-102.5% with RSDs all below 9.4%. The present method has been successfully applied for the sensitive determination of trace four OH-PAHs in urine samples from non-smokers and smokers with a maximum concentration of 2.24 and 3.56 ng mL-1, respectively, which showed a great potential for the analysis of trace OH-PAHs in biological samples.

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.