Rapid determination of anilines in water samples by dispersive liquid–liquid microextraction based on solidification of floating organic drop prior to gas chromatography–mass spectrometry

In-syringe homogeneous liquid-phase microextraction followed by filtration-based phase separation for on-site extraction of chloroanilines from water samples

This study introduces a new in-syringe homogeneous liquid-phase microextraction method for the rapid on-site extraction of chloroanilines from water samples. Extraction was performed using a plastic syringe, eliminating the use of any electrical power source. Di-(2-ethylhexyl) phosphoric acid (DEHPA) served as the extractant. The process initially involved dissolving DEHPA in an alkaline solution to obtain a homogeneous solution. Subsequently, the sodium salt of DEHPA was precipitated by salting-out, and the resulting heterogeneous mixture was filtered using a syringe filter. The precipitate containing the analytes was then dissolved in methanol for analysis by high-performance liquid chromatography. Under optimal conditions, extraction recovery for chloroanilines ranged from 26% to 71%. Method linearity was evaluated within a concentration range of 1.0-100 µg/L, resulting in coefficients of determination exceeding 0.9987 for all analytes. Method detection limits ranged from 0.28 to 0.41 µg/L. Intra and inter-day precision values were below 9.5% and 10.8%, respectively. The developed method was applied to determine chloroanilines in real waters, yielding acceptable recoveries ranging from 80% to 109% for spiked tap, rain, and stream waters. Additionally, the method was successfully employed for on-site extraction of target contaminants, demonstrating no statistically significant differences compared to laboratory results.

Chromatographic Separation of Aromatic Amine Isomers: A Solved Issue by a New Amphiphilic Pillar[6]arene Stationary Phase

In this work, the fabrication, synthesis, and characterization of a new stationary phase based on an amphiphilic pillar[6]arene (P6A-C10-2NH₂) for gas chromatographic analyses are reported. The gas chromatography (GC) column prepared with P6A-C10-2NH₂ stationary phase exhibited a medium polarity, an efficiency of 3219 plates/m, and unmatched resolving capabilities toward chloroaniline, bromoaniline, iodoaniline, and toluidine isomers. Furthermore, the P6A-C10-2NH₂ column showed excellent repeatability with maximum relative standard deviations equal to 0.02, 0.07, and 2.56% for run-to-run, day-to-day, and column-to-column, respectively, demonstrating a great potential as a new stationary phase in separation science.

Polymeric metal-containing ionic liquid sorbent coating for the determination of amines using headspace solid-phase microextraction

This study describes the design, synthesis, and application of polymeric ionic liquid sorbent coatings featuring nickel metal centers for the determination of volatile and semivolatile amines from water samples using headspace solid-phase microextraction. The examined polymeric ionic liquid (PIL) sorbent coatings were composed of two ionic liquid monomers (tetra(3-vinylimidazolium)nickel bis[(trifluoromethyl)sulfonyl]imide [Ni²⁺ (VIM)₄ ] 2[NTf₂ ^- ] and 1-vinyl-3-hexylimidazolium [HVIM⁺ ][NTf₂ ^- ]), and an ionic liquid cross-linker (1,12-di(3-vinylimidazolium)dodecane  [(VIM)₂ C₁₂ ²⁺ ] 2[NTf₂ ^- ]). With these ionic liquid monomers and cross-linkers, three different types of coatings were prepared: PIL 1 based on the neat [Ni²⁺ (VIM)₄ ] 2[NTf₂ ^- ] monomer, PIL 2 consisting of the [Ni²⁺ (VIM)₄ ] 2[NTf₂ ^- ] monomer with addition of cross-linker, and PIL 3 composed of the [HVIM⁺ ][NTf₂ ^- ] monomer and cross-linker. Analytical performance of the prepared sorbent coatings using headspace solid-phase microextraction gas chromatography-mass spectrometry was compared with the polydimethylsiloxane and polyacrylate commercial coatings. The PIL 2 sorbent coating yielded the highest enrichment factors ranging from 5500 to over 160 000 for the target analytes. The developed headspace solid-phase microextraction gas chromatography-mass spectrometry method was applied for the analysis of real samples (the concentration of amines was 200 μg/L), producing relative recovery values in the range of 90.9-120.0% (PIL 1) and 83.0-122.7% (PIL 2) from tap water, and 84.8-112.4% (PIL 1) and 79.2-119.3% (PIL 2) from lake water.