Simultaneous determination of seven nitrogen-containing phenyl ethers in cosmetics by gas chromatography with mass spectrometry and dispersive solid-phase extraction.

An analytical method was established for the simultaneous determination of seven nitrogen-containing phenyl ethers (2-anisidine, 3-anisidine, 4-anisidine, 2-nitroanisole, 3-nitroanisole, 4-nitroanisole, and 3,3'-dimethoxybenzidine) in cosmetics by gas chromatography with mass spectrometry in this work. The samples were extracted with ethyl acetate and purified with primary secondary amine during the dispersed solid-phase extraction. The analytes were separated by a DB-17MS column and detected in the electron ionization mode of mass spectrometry in the selected ions monitoring mode. The extraction solvent, purification adsorbents, and chromatographic column behavior were optimized. The results indicated that the seven analytes show good linear relationship (R2 > 0.9965) in the concentrations of 5.0-5000 µg/L. The quantitation limits of the method ranged from 19.0 to 84.8 µg/kg. The recovery rates of seven analytes were in the range of 72.6-114% with the relative standard deviations of 1.1-7.5%. Real sample analyses showed that this accurate and precise method could be appropriate for simultaneous determination of seven nitrogen-containing phenyl ethers in cosmetics.

Conjugated Microporous Polymers with Built-In Magnetic Nanoparticles for Excellent Enrichment of Trace Hydroxylated Polycyclic Aromatic Hydrocarbons in Human Urine.

Conjugated microporous polymers (CMPs), linked by a covalent bond to form an extension of the aromatic ring skeleton, are microporous materials characterized by a highly conjugated structure and high stability. The present study reported on a novel strategy for the synthesis of CMPs with built-in magnetic nanoparticles for excellent enrichment of trace hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) in human urine. We modified Fe3O4 nanoparticles with boronic acid groups and then reacted the nanoparticles with reactive monomers of polyphenylene conjugated microporous polymer (PP-CMP) to anchor the magnetic components in the PP-CMP framework. Chemical bonding between Fe3O4 nanoparticles and PP-CMP networks, together with equally firm covalent linkage and rigidity of the PP-CMP network, endows the magnetic PP-CMP with remarkable chemical stability and durability, even in harsh conditions. Magnetic PP-CMP has the characteristics of high conjugation ability, highly porous structure, and magnetism, which makes it an ideal magnetic adsorbent for trace analytes with aromatic conjugation structure. The adsorption mechanism of OH-PAHs on magnetic PP-CMP was investigated and demonstrated that hydrophobic interaction was important for the contribution of interaction between adsorbents and target analytes, together with the assistance of π-π stacking interaction. For the application, the magnetic PP-CMP was used for the enrichment of trace OH-PAHs in human urine of both smokers and nonsmokers in combination with high-performance liquid chromatography with fluorescence detection (HPLC-FLD). It showed good selectivity and excellent sensitivity to these OH-PAHs. Their detection limits were low and in the range of 0.01-0.08 µg·L(-1). The OH-PAHs were detected with different amounts from 0.054 to 0.802 µg·L(-1) in urine samples from smokers and nonsmokers. The recoveries were found to be 76.0%-107.8%. The results indicate that the magnetic PP-CMP offers an efficient enrichment method for trace OH-PAHs in human urine.

In situ solvothermal growth of metal-organic framework-5 supported on porous copper foam for noninvasive sampling of plant volatile sulfides.

The present study reported on an in situ solvothermal growth method for immobilization of metal-organic framework MOF-5 on porous copper foam support for enrichment of plant volatile sulfides. The porous copper support impregnated with mother liquor of MOF-5 anchors the nucleation and growth of MOF crystallites at its surface, and its architecture of the three-dimensional channel enables accommodation of the MOF-5 crystallite seed. A continuous and well-intergrown MOF-5 layer, evidenced from scanning electron microscope imaging and X-ray diffraction, was successfully immobilized on the porous metal bar with good adhesion and high stability. Results show that the resultant MOF-5 coating was thermally stable up to 420 °C and robust enough for replicate extraction for at least 200 times. The MOF-5 bar was then applied to the headspace sorptive extraction of the volatile organic sulfur compounds in Chinese chive and garlic sprout in combination with thermal desorption-gas chromatography/mass spectrometry. It showed high extraction sensitivity and good selectivity to these plant volatile sulfides owing to the extraordinary porosity of the metal-organic framework as well as the interaction between the S-donor sites and the surface cations at the crystal edges. Several primary sulfur volatiles containing allyl methyl sulfide, dimethyl disulfide, diallyl sulfide, methyl allyl disulfide, and diallyl disulfide were quantified. Their limits of detection were found to be in the range of 0.2-1.7 µg/L. The organic sulfides were detected in the range of 6.0-23.8 µg/g with recoveries of 76.6-100.2% in Chinese chive and 11.4-54.6 µg/g with recoveries of 77.1-99.8% in garlic sprout. The results indicate the immobilization of MOF-5 on copper foam provides an efficient enrichment formats for noninvasive sampling of plant volatiles.

Synthesis of nanoscale titania embedded in MIL-101 for the adsorption and degradation of volatile pollutants with thermal desorption gas chromatography and mass spectrometry detection.

Nanoscale anatase titania was embedded within the porous chromium terephthalate MIL-101 under low-temperature hydrothermal treatment. The metal-organic framework shell acting as host matrix can effectively prevent the titania nanoparticles from aggregating and enable a good dispersion of these nanoparticles. The X-ray diffraction spectra, transmission electron micrography and X-ray photoelectron spectra clearly showed successful impregnation of the nano-sized anatase titania within the body of MIL-101. The resulting TiO2/MIL-101 nanocomposite was considered as bifunctional material with abundant adsorptive domains and catalytic domains, and was packed in a quartz tube as a convenient trapping and photocatalytic reactor for hazardous volatile pollutants. The composite showed great potential for adsorptive and photocatalytic degradation of these volatile pollutants, such as formaldehyde and o-xylene, which were online monitored by thermal desorption gas chromatography with mass spectrometric detection.