Development of new polar monolithic coatings for stir bar sorptive extraction

Overview of Sample Preparation and Chromatographic Methods to Analysis Pharmaceutical Active Compounds in Waters Matrices

In the environment, pharmaceutical residues are a field of particular interest due to the adverse effects to either human health or aquatic and soil environment. Because of the diversity of these compounds, at least 3000 substances were identified and categorized into 49 different therapeutic classes, and several actions are urgently required at multiple steps, the main ones: (i) occurrence studies of pharmaceutical active compounds (PhACs) in the water cycle; (ii) the analysis of the potential impact of their introduction into the aquatic environment; (iii) the removal/degradation of the pharmaceutical compounds; and, (iv) the development of more sensible and selective analytical methods to their monitorization. This review aims to present the current state-of-the-art sample preparation methods and chromatographic analysis applied to the study of PhACs in water matrices by pinpointing their advantages and drawbacks. Because it is almost impossible to be comprehensive in all PhACs, instruments, extraction techniques, and applications, this overview focuses on works that were published in the last ten years, mainly those applicable to water matrices.

Development of a carbon-nanoparticle-coated stirrer for stir bar sorptive extraction by a simple carbon deposition in flame

Stir bar sorptive extraction is an environmentally friendly microextraction technique based on a stir bar with various sorbents. A commercial stirrer is a good support, but it has not been used in stir bar sorptive extraction due to difficult modification. A stirrer was modified with carbon nanoparticles by a simple carbon deposition process in flame and characterized by scanning electron microscopy and energy-dispersive X-ray spectrometry. A three-dimensional porous coating was formed with carbon nanoparticles. In combination with high-performance liquid chromatography, the stir bar was evaluated using five polycyclic aromatic hydrocarbons as model analytes. Conditions including extraction time and temperature, ionic strength, and desorption solvent were investigated by a factor-by-factor optimization method. The established method exhibited good linearity (0.01-10 μg/L) and low limits of quantification (0.01 μg/L). It was applied to detect model analytes in environmental water samples. No analyte was detected in river water, and five analytes were quantified in rain water. The recoveries of five analytes in two samples with spiked at 2 μg/L were in the range of 92.2-106% and 93.4-108%, respectively. The results indicated that the carbon nanoparticle-coated stirrer was an efficient stir bar for extraction analysis of some polycyclic aromatic hydrocarbons.

Analysis of drugs in plasma samples from schizophrenic patients by column-switching liquid chromatography-tandem mass spectrometry with organic-inorganic hybrid cyanopropyl monolithic column

This study reports on the development of a rapid, selective, and sensitive column-switching liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to analyze sixteen drugs (antidepressants, anticonvulsants, anxiolytics, and antipsychotics) in plasma samples from schizophrenic patients. The developed organic-inorganic hybrid monolithic column with cyanopropyl groups was used for the first dimension of the column-switching arrangement. This arrangement enabled online pre-concentration of the drugs (monolithic column) and their subsequent analytical separation on an XSelect SCH C18 column. The drugs were detected on a triple quadrupole tandem mass spectrometer (multiple reactions monitoring mode) with an electrospray ionization source in the positive ion mode. The developed method afforded adequate linearity for the sixteen target drugs; the coefficients of determination (R(2)) lay above 0.9932, the interassay precision had coefficients of variation lower than 6.5%, and the relative standard error values of the accuracy ranged from -14.0 to 11.8%. The lower limits of quantification in plasma samples ranged from 63 to 1250pgmL(-1). The developed method successfully analyzed the target drugs in plasma samples from schizophrenic patients for therapeutic drug monitoring (TDM).

Two polydimethylsiloxane rod extraction methods for the sensitive determination of phenolic compounds in water samples

Simple, precise, and low-cost methods for the simultaneous determination of phenolic endocrine disrupting compounds such as bisphenol A, trichlorophenol, pentachlorophenol, 4-nonylphenol, and 4-octylphenol in water samples were developed. The Direct, in situ derivatization methods are based on polydimethylsiloxane rod extraction followed by liquid desorption and chromatographic analysis by liquid chromatography and diode array detection. Several parameters affecting the extraction and desorption of the phenolic compounds and their acetylated derivates were studied, as well as the chromatographic and detection conditions. For the direct method, determination coefficients (r(2) ) > 0.990 and LODs in the 0.6-2 μg/L range were obtained for all compounds except bisphenol A (9.5 μg/L). With the derivatization-based method, based on in situ acetylation, lower limits of detection (0.3-0.9 μg/L) were obtained for all the compounds with r(2) > 0.988 and RSDs in the 2-9% range. The developed methods were applied to the analysis of spiked water samples obtaining recoveries of between 60.2 and 131.7% for the direct method, and of between 76.6 and 108.2% for the derivatization-based method. The results demonstrate the feasibility of using these two methods for determining bisphenol A, trichlorophenol, pentachlorophenol, 4-nonylphenol, and 4-octylphenol in water.