Determination of aniline and its derivatives in environmental water by capillary electrophoresis with on-line concentration

Rearranged Copolyurea Networks for Selective Carbon Dioxide Adsorption at Room Temperature

Copolyurea networks (co-UNs) were synthesized via crosslinking polymerization of a mixture of tetrakis(4-aminophenyl)methane (TAPM) and melamine with hexamethylene diisocyanate (HDI) using the organic sol-gel polymerization method. The subsequent thermal treatment of between 200 and 400 °C induced the sintering of the powdery polyurea networks to form porous frameworks via urea bond rearrangement and the removal of volatile hexamethylene moieties. Incorporating melamine into the networks resulted in a higher nitrogen content and micropore ratio, whereas the overall porosity decreased with the melamine composition. The rearranged network composed of the tetraamine/melamine units in an 80:20 ratio showed the highest carbon dioxide adsorption quantity at room temperature. The results show that optimizing the chemical structure and porosity of polyurea-based networks can lead to carbon dioxide adsorbents working at elevated temperatures.

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.

Determination of primary aromatic amines from cooking utensils by capillary electrophoresis-tandem mass spectrometry

This paper describes a fast, sensitive, environment-friendly method for the determination of 19 primary aromatic amines (PAAs) in cooking utensils by capillary zone electrophoresis coupled with tandem mass spectrometry. The best electrophoretic separation of PAAs was obtained in 0.1 mol l^-1 formic acid (pH 2.4) as the background electrolyte, fused silica capillary (67 cm) with a run time below 6 min. The proposed method presented a linear calibration with correlation coefficients higher than 0.99 and reproducibility in a range of 1-25%. Limits of detection were in the range of 0.2-1.3 μg kg^-1 and recoveries were in a range of 85-120% for all the PAAs. The validated method was employed to determine PAAs on 36 samples of cooking utensils using acetic simulant. The results showed that 4,4'-diaminodiphenylmethane and aniline being the most frequently found PAAs in these samples and 28% of cooking utensils were not compliant.

Development of an LC-MS Method for 4-Fluoroaniline Determination in Ezetimibe

A rapid and sensitive high-performance liquid chromatography-mass spectrometry method was developed and validated to determine 4-fluoroaniline concentration in ezetimibe. Chromatographic separation was achieved on a Phenomenex Gemini-NX C18 column (150 × 4.6 mm, 3 μm) maintained at 30°C. The liquid chromatography system was operated in gradient mode with an injection volume of 20 μL at a flow rate of 1 mL/min. Mobile phase A was water and mobile phase B consisted of acetonitrile with 0.05% acetic acid. The detection was performed using a single quadrupole mass spectrometer in single ion monitoring mode by using positive ionization. An m/z value of 112 was selected for monitoring 4-fluoroaniline. The method showed good linearity over the concentration range of 0.94-30.26 ng/mL. The limit of quantification and limit of detection were 0.19 and 0.94 ng/mL, respectively. The precision relative standard deviations were less than 8.7% (n = 12), and the accuracy values were within 92-99%. A standard solution of 4-fluoroaniline was stable for at least 24 h at 25°C. Small changes in the organic phase acidity of the mobile phase, flow rate, column temperature, and the instrument parameters had no significant effect on the results for 4-fluoroaniline.

Colorimetric and fluorometric dual-mode detection of aniline pollutants based on spiropyran derivatives

The selective UV-vis absorption of spiropyran and the fluorescence quenching of SP-cellulose material induced by aniline were observed and exploited for rapid detection and accurate quantitative determination of aniline pollutants in the environment.