Fast and sensitive determination of 10 forbidden phthalates in perfumes by ultra-high performance liquid chromatography-electrospray ionization-tandem mass spectrometry.

A fast and sensitive ultra-high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UHPLC-ESI-MS/MS) method was developed for simultaneously analyzing 10 phthalates in perfume, which are forbidden by the hygienic standards for cosmetics in China (2007 edition). Matrix effect is significant on a phthalate when it is co-eluted with other phthalates. Improving the resolution between adjacent phthalate peaks is found effective in reducing the matrix effects. Thus, simultaneous analysis of the 10 phthalates requires successful resolutions of each phthalate. Nonetheless, a trade-off between the resolution and analysis time results either incomplete separation or prolonged analysis time. Here, the UHPLC elution gradient is optimized considering the predicted retention time of each phthalate. The resolutions and matrix effects of targeted compounds are evaluated to determine the optimal elution gradient for UHPLC-MS analysis method. Under the optimized gradient, the resolution between closest phthalate peaks is beyond 1.7, while the analysis time is merely 7 min. Except for dimethyl phthalate (DMP) and dicyclohexyl phthalate (DCHP), insignificant matrix effects have been found on all the phthalates. Direct quantifications through external calibration curve are appropriate for such analytes. Nonetheless, DMP and DCHP suffering obvious matrix effects require extra analyses of spiked samples for the quantifications through the standard addition method. Instrumental limits of quantitation (iLOQs) are 0.12-89 µg L-1 for the targeted phthalates. Meanwhile, the accuracy and precision of the analytical method are good. Finally, the forbidden phthalates in 26 sampled perfumes are successfully analyzed by the developed method.

ß-Cyclodextrin Covalent Organic Framework for Selective Molecular Adsorption.

Covalent organic frameworks (COF) are complex functional systems constructed with atomic precision by linking well-defined building blocks through robust covalent bonds. ß-cyclodextrin (ß-CD) is a most employed supramolecule which bears a hydrophobic cavity guiding molecular specific recognitions. Building COF with asymmetric ß-CD linkers is challenging and has never been reported. Here, ß-CD COF is grown with heptakis(6-amino-6-deoxy)-ß-CD and terephthalaldehyde in green solvents of water and ethanol at room temperature. The COF is characterized by powder X-ray diffraction, which matches well with the simulated crystal structure. Weaving ß-CD into a framework through reticular chemistry allows the integration of a large amount of ß-CD units (50 mol %), much higher than ß-CD polymers. The ß-CD COF has larger surface area, more uniform pore size, and higher thermal stability than the non-crystalline ß-CD polymer produced by the same reagents. Finally, the ß-CD COF holds abundant specific interaction sites enabling selective molecular adsorption.