No abstract

A novel Pb(II) ion-imprinted chelating nanofibers (nIIP), synthesized by combining electrospinning with surface ion imprinting technique, was reported in this study. nIIP was characterized with Fourier transmission infrared spectrometry and scanning electron microscopy, respectively. The performance of nIIP for Pb(II) sorption was conducted through a batch adsorption experiments. Experimental data showed that adsorption capacity of nIIP was much higher than that of non-ion imprinted chelating acrylic microfibers (mNIP) derived from commercial available acrylic microfibers, and adsorption behaviors agreed well with pseudo-second-order kinetic and Langmuir isotherm model. The values of Gibbs free energy change derived from experimental data suggested that the adsorption Pb(II) on nIIP is spontaneous and favorable at high temperature. In addition, nIIP had the highest selectivity among three tested fibrous adsorbents for Pb(II) from binary metal solution, the selectivity coefficients for Pb(II) from binary metal solution of Pb(II)/Cu(II), Pb(II)/Ni(II), and Pb(II)/ Cd(II) onto nIIP were 47, 101, and 162, respectively. Besides, a forty adsorption/desorption cycles revealed that nIIP was a promising recyclable adsorbent. In conclusion, the novel nIIP is a highly effective adsorbent for enrichment and separation of Pb(II) in the presence of competitive ions in aqueous solution, and it is potential to be applied for recovering metals from heavy metal polluted industrial wastewater such as Pb(II)/Cd(II), Pb(II)/Ni(II), and Pb(II)/Cu(II) polluted wastewater.

A rapid, sensitive, and practical QuEChERS method coupled with gas chromatography-mass spectrometry was developed for the simultaneous determination of 16 chemical adjuvant residues in samples of fruits (apple, nectarine, grape) and vegetables (tomato, cucumber, spinach). All target compounds were separated in less than 16 min. Samples were extracted with acetonitrile, and the types of extraction salt and cleanup sorbent were optimized. The optimized method was validated by evaluating the linearity, accuracy, precision, and matrix effect. The recoveries of the 16 pesticides adjuvants ranged from 61.2 to 116.3% with relative standard deviations lower than 11.6%. Limits of detection ranged from 0.21 to 3.02 μg/kg, and limits of quantification ranged from 0.71 to 10.07 μg/kg. Finally, the developed method was successfully employed to identify and quantify pesticide adjuvant residues in the analysis of 30 real fruit and vegetable samples.

A UPLC-MS/MS method was developed for simultaneous determination of 7 whitening ingredients: nicotinamide, kojic acid, Tranexamic acid, raspberry glycoside, azelaic acid, magnesium ascorbate phosphate and β-Arbutin in cosmetics. The whitening active components were extracted from cosmetics by supersonic extraction with sodium chloride and dichloromethane to disperse the sample, and supersonic extraction with 0.015 mol/L potassium dihydrogen phosphate solution purified by HLB solid phase extraction column, scanned and detected by electrospray ionization source with positive and negative ion alternate scanning mode and multiple reaction monitoring mode. The results showed that the whitening active ingredients were separated within 3 minutes, with a good linear relationship (R>0.999), and the detection limit was 0.10mg/kg~0.75mg/kg. The recoveries (n=6) were 78.84%-104.85%, and the RSDs were 0.24%-11.35%. This method is suitable for the rapid determination of whitening active ingredients in cosmetics.