Rapid analysis of six trace trichlorophenols in seawater by magnetic micro-solid-phase extraction and liquid chromatography with tandem mass spectrometry

Piperazine-linked metal covalent organic framework-coated fibers for efficient electro-enhanced solid-phase microextraction of chlorophenols

Conductive covalent organic frameworks (COFs) have received considerable attention and are critical in various applications such as electro-enhanced solid-phase microextraction (EE-SPME). In this work, a novel piperazine-linked copper-doped phthalocyanine metal covalent organic framework (CuPc-MCOF) was synthesized with good stability and high electrical conductivity. The synthesized CuPc-MCOF was then used as an EE-SPME coating material for extraction of five trace chlorophenols (CPs), including 2,4-dichlorophenol (2,4-DCP), 2,6-dichlorophenol (2,6-DCP), 2,4,6-trichlorophenol (2,4,6-TCP), 2,4,5-trichlorophenol (2,4,5-TCP) and 2,4,5,6-tetrachlorophenol (2,4,5,6-TCP), exhibiting excellent extraction performance because of various synergistic forces between CuPc-MCOF fibers and CPs. By combining EE-SPME with gas chromatography-tandem mass spectrometry (GC-MS/MS), a sensitive method for CPs detection was established with a low limit of detection (0.8-5 ng L^-1) and good reproducibility (RSD≤8.4%, n = 3). This method was then successfully applied to the analysis of trace CPs in real samples of seawater and seafood. Results showed that the developed CuPc-MCOF coating material possessed superior extraction performance and potential application in extraction of trace polar pollutants from complex samples.

Monitoring of priority pollutants chlorophenols in water and milk by headspace solid-phase microextraction based on electrospun polycaprolactam nanofibers decorated with cadmium oxide-carbon nanotubes

Priority pollutants chlorophenols are broadly used chemicals that are persistent in the environment and causing serious human health hazards. The current study introduces a novel adsorbent for the extraction of chlorophenols from river water, surface water, and milk by headspace solid-phase microextraction coupled with gas chromatography. The adsorbent composite was prepared by blending polycaprolactam (nylon-6) mat and newly synthesized carbon nanotubes decorated with cadmium oxide nanoparticles followed by electrospinning technique to produce based nanofiber. The proposed nanofiber was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction techniques. The main parameters that affect extraction efficiency, including ionic strength, extraction time, desorption time, and extraction temperature, were investigated and optimized. The linear range was 0.05-5 ng/mL; the limits of detection (signal/noise=3) were 0.02-0.04 ng/mL. The relative recoveries for real samples (river water, surface water, and milk) were in the range of 84-114%.

Dispersive liquid-liquid microextraction coupled with pressure-assisted electrokinetic injection for simultaneous enrichment of seven phenolic compounds in water samples followed by determination using capillary electrophoresis

Offline dispersive liquid-liquid microextraction combined with online pressure-assisted electrokinetic injection was developed to simultaneously enrich seven phenolic compounds in water samples, followed by determination using capillary electrophoresis, namely phenol, 4-chlorophenol, pentachlorophenol, 2,4,6-trichlorophenol, 2,4-dichlorophenol, 2-chlorophenol, and 2,6-dichlorophenol. Several parameters affecting separation performance of capillary electrophoresis and the enrichment efficiency of pressure-assisted electrokinetic injection and dispersive liquid-liquid microextraction were systematically investigated. Under the optimal conditions, seven phenolic compounds were completely separated within 14 min and good enrichment factors were obtained of 61, 236, 3705, 3288, 920, 86, and 1807 for phenol, 4-chlorophenol, pentachlorophenol, 2,4,6-trichlorophenol, 2,4-dichlorophenol, 2-chlorophenol, and 2,6-dichlorophenol, respectively. Good linearity was attained in the range of 0.1-200 μg/L for 2,4-dichlorophenol, 0.5-200 μg/L for 4-chlorophenol, pentachlorophenol, 2,4,6-trichlorophenol, 2-chlorophenol, and 2,6-dichlorophenol, as well as 1-200 μg/L for phenol, with correlation coefficients (r) over 0.9905. The limits of detection and quantification ranging from 0.03-0.28 and 0.07-0.94 μg/L were attained. This two step enrichment method was potentially applicable for the rapid and simultaneous determination of phenolic compounds in water samples.