Synthesis and Properties of a Bay-Annulated-Indigo Tetramer Based on Low-Cost Spiro[Fluorene-9,9'-Xanthene] Core.

A three-dimensional bay-annulated-indigo (BAI) tetramer has been prepared by appending BAI units onto a low-cost spiro[fluorene-9,9'-xanthene] (SFX) core. The target compound 4BAI-SFX exhibits strong and broad absorption in the visible region covering the range of 450~700 nm. The electrochemical measurement illuminates the characteristics of a deep lowest unoccupied molecular orbital (LUMO) level and multiple redox states of 4BAI-SFX. These results suggest that 4BAI-SFX should be a selectable electron-transporting material for eco-friendly organic semiconductors.

A novel mixed-mode solid phase extraction for simultaneous determination of melamine and cyanuric acid in food by hydrophilic interaction chromatography coupled to tandem mass chromatography.

Utilizing a solid phase extraction column (MCT) containing mixed hydrophilic functional gel and cation exchange sorbent, a sensitive and rapid HPLC-MS/MS method for simultaneously determining the residues of melamine (MEL) and cyanuric acid (CYA) in human foodstuffs was developed. MEL and CYA in egg, pork, liver, kidney and pork, shrimp, sausage casing, honey, soybean milk, soybean powder and dairy product were extracted using acetonitrile/water, defatted with hexane and isolated using MCT solid phase extraction column. The residues were separated upon a hydrophilic interaction liquid chromatography (HILIC) column and analyzed by electrospray ionization under negative-positive switched mode on a triplequadrupole mass spectrometry. The selected reaction monitoring was performed on [M+H](+) of m/z 127.9 to provide the transition of 127>85 and 127>68 (MEL) while the [M-H](-) of m/z 127.1 was selected as the precursor ion for CYA resulting in product ions m/z 85 and 42. Isotope labeled internal standard ((15)N(3)-MEL and (13)C(3)-CYA) and matrix-matched calibration were both used to observe the recovery to be 70.0-129.6% and 70.0-128.9% with RSD of 1.4-23.3% and 1.5-21.7% for MEL and CYA, respectively (n=6). All the LODs and LOQs of MEL and CYA were less than 39.4 and 99.1µgkg(-1), respectively, in 18 matrices, which were sensitive enough for quantitative analysis. This method has been proven effective in simultaneous determination of melamine and cyanuric acid when inspecting unknown and positive samples.