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The determination of multiple per- and polyfluoroalkyl substances (PFAS) migrating from food contact material gained in importance as an increasing range of PFAS has been found migrating from food contact material into food. In this study, an integrated analytical approach that combines high performance liquid chromatography- tandem mass spectrometry (HPLC-MS/MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS) was established for detecting 36 PFAS migrating from food contact materials into four food simulants (3% acetic acid, 10% alcohol, 50% alcohol, and olive oil). The response surface methodology was applied to optimize the selection of solvents in sample treatment. This target analytical method was appropriate for the determination of multiple PFAS, with recoveries ranging from 81.8 to 118.7%. The relative standard deviations (RSDs) ranged from 2.4 to 7.8%, and detection limits were in the range of 0.3 to 10 μg/kg in relevant food simulants. [ABSTRACT FROM AUTHOR]

Split-ring resonator (SRR) metamaterials are introduced in the design of a multilayer filter Considering the electric coupling to the magnetic resonance, careful examination of the SRR orientations to the external stimulation is presented through full wave analysis. With the skew-symmetric feed scheme, the compact multilayer filter has a center frequency of 6.07 GHz and 7 percent fractional bandwidth with two transmission zeros at 5.79 and 7.1 GHz, Compared with a conventional microstrip filter, the proposed filter shows a significant size reduction and improved selectivity. [ABSTRACT FROM AUTHOR]

Split ring resonator (SRR) metamaterials are introduced to the design of a multilayer filter. Considering the electrical coupling to the magnetic resonance, careful examination of SRR orientations to the external stimulation is presented through a full wave analysis. With the skew-symmetric feed scheme, the compact multilayer filter has a center frequency of 6.07 GHz and 7 percent fractional bandwidth with two transmission zeros at 5.79 and 7.1 GHz. Compared with the conventional microstrip filter, the pro posed filter shows a significant size reduction and improved selectivity. [ABSTRACT FROM AUTHOR]

The use of superficially porous particles (SPPs) for modern high performance liquid chromatography (HPLC) is now very common. Initially, SPPs rose as an alternative to sub-2-μm fully porous particles (FPPs). In recent years, many column manufacturers have developed 2-μm and smaller SPP-based products. This article investigates the practical utility of these smaller SPP designs. [ABSTRACT FROM AUTHOR]