Covalent organic nanospheres modified magnetic nanoparticles for extraction of blood lipid regulators in water samples.

Covalent organic nanospheres are new kind of nanospherical polymer with large specific surface area, uniform morphology, and excellent chemical and thermal stability. This material can be fabricated by a facile and rapid room temperature solution-phase strategy. In this work, magnetic nanoparticles were attached to the surface of covalent organic nanospheres, and the obtained composites were used for the extraction of blood lipid regulators such as clofibrate and fenofibrate. These composites were characterized with Fourier-transformed infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. Several parameters that might affect the extraction efficiency including acetonitrile content, pH value, extraction time, and sample volume were investigated. Under optimum conditions, the proposed analytical method showed high extraction efficiency toward clofibrate and fenofibrate with enrichment factors between 60 and 83. This method exhibited outstanding analytical performance with wide linear range and excellent reproducibility and had low limits of detection in the range of 0.02-0.03 ng/mL. This method was also applied to the detection of clofibrate and fenofibrate in lake water samples, and good recoveries in the range of 92.6-112.6% was obtained.

Occurrence of fibrates and their metabolites in source and drinking water in Shanghai and Zhejiang, China.

Fibrates, which are widely used lipidaemic-modulating drugs, are emerging environmental pollutants. However, fibrate concentrations in the environment have not been thoroughly surveyed. Here, we determined concentrations of the most commonly used fibrates and their metabolites in source water and drinking water samples from ten drinking water treatment plants in Shanghai and Zhejiang, China, using solid-phase extraction and liquid chromatography-tandem mass spectrometry. All the target compounds were detected in at least some of the source water samples, at concentrations ranging from 0.04 ng/L (fenofibrate) to 1.53 ng/L (gemfibrozil). All the compounds except fenofibrate were also detected in at least some of the drinking water samples, at recoveries ranging from 35.5% to 91.7%, suggesting that these compounds are poorly removed by typical drinking water treatment processes. In a peroxisome proliferator-activated receptor α agonistic activity assay, the target compounds showed no significant activity at nanogram per litre concentrations; therefore, our results suggest that the fibrate concentrations in drinking water in Shanghai and Zhejiang, China do not significantly affect human health. However, because of the increasing westernization of the Chinese diet, fibrate use may increase, and thus monitoring fibrate concentrations in aquatic environments and drinking water in China will become increasingly important.

An automated method for the simultaneous determination of pravastatin, 3-hydroxy isomeric metabolite, pravalactone and fenofibric acid in human plasma by sensitive liquid chromatography combined with diode array and tandem mass spectrometry detection.

In this study, a sensitive and selective method based on liquid chromatography combined with diode array and tandem mass spectrometry detection (LC-DAD-MS/MS) was developed for the simultaneous quantitative determination of fenofibric acid, pravastatin and its main metabolites in human plasma. In this method, an automated solid-phase extraction (SPE) on disposable extraction cartridges (DECs) is used to isolate the compounds from the biological matrix and to prepare a cleaner sample before injection and analysis in the LC-DAD-MS/MS system. On-line LC-DAD-MS/MS system using an atmospheric pressure ionization (TurboIonSpray) was then developed for the simultaneous determination of pravastatin, 3-hydroxy isomeric metabolite (3-OH metab), pravalactone and fenofibric acid. The separation is obtained on an endcapped dodecyl silica based stationary phase using a mobile phase consisting of a mixture of acetonitrile, methanol and 5mM ammonium acetate solution (30:30:40, v/v/v). Sulindac and triamcinolone were used as internal standards (ISs). The detection of the fenofibric acid and sulindac was achieved by means of a DAD system. The MS/MS ion transitions monitored were m/z 442.2-->269.1, 442.2-->269.1, 424.3-->183.0 and 435.2-->397.2 for pravastatin, 3-OH metab, pravalactone and triamcinolone, respectively. The method was validated regarding stability, selectivity, extraction efficiency, response function, trueness, precision lower limit of quantitation and matrix effect. The limits of quantitation (LOQs) were around 0.50 ng/ml for pravastatin, 0.25 ng/ml for 3-OH metab, 0.05 ng/ml for pravalactone and 0.25 microg/ml for fenofibric acid.