A Highly Sensitive and High-Resolution Resonant MEMS Electrostatic Field Microsensor Based on Electrostatic Stiffness Perturbation.

This paper proposes a highly sensitive and high-resolution resonant MEMS electrostatic field sensor based on electrostatic stiffness perturbation, which uses resonant frequency as an output signal to eliminate the feedthrough interference from the driving voltage. The sensor is composed of a resonator, driving electrode, detection electrode, transition electrode, and electrostatic field sensing plate. The working principle is that when there is an electrostatic field, an induction charge will appear at the surface of the electrostatic field sensing plate and induce electrostatic stiffness on the resonator, which will cause a resonant frequency shift. The resonant frequency is used as the output signal of the microsensor. The characteristics of the electrostatic field sensor are analyzed with a theoretical model and verified by finite element simulation. A device prototype is fabricated based on the Silicon on Insulator (SOI) process and tested under vacuum conditions. The results indicate that the sensitivity of the sensor is 0.1384Hz/(kV/m) and the resolution is better than 10 V/m.

Application of dispersive liquid-liquid microextraction based on solidification of floating organic drop for the determination of extractables from pharmaceutical packaging materials.

A new method was established for the determination of the extractables from pharmaceutical packaging materials using dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) coupled with ultra-high-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF MS). Packaging samples were filled with three kinds of buffer solutions: acid buffer (pH = 3), alkaline buffer (pH = 9) and 0.9% NaCl solution to extract as many extractables as possible, and then the extractables in buffer solutions were enriched by DLLME-SFO technique. Parameters affecting the efficiency of the extraction procedure were evaluated and optimized, including the type and volume of dispersant, extractant volume, pH and vortex-mixing time. After optimization, the values obtained for limits of detection and quantification for three kinds of common antioxidants were 0.3 and 1.0 µg/L respectively, and good linearity (R2 > 0.99) was observed in their respective concentration ranges. The recoveries ranged from 80.61% to 117.87% at three spiked levels with the relative standard deviations (RSDs) between 0.92% and 9.29% (n = 6) in all three buffer solutions. The developed method was successfully applied to the analysis of extractables from pharmaceutical packaging materials. The results indicated that the proposed procedure is a novel, sensitive, fast and repeatable method and has a great significance for evaluation of safety of pharmaceutical packaging materials.

Fabric-phase sorptive extraction coupled with ion mobility spectrometry for on-site rapid detection of PAHs in aquatic environment.

The contamination of water is a high risk to human health, so there is an urgent need to rapidly detect water pollution in the field. Ion mobility spectrometry (IMS) is suitable for on-site analysis with the merit of rapid analysis and compact size. In this study, we developed a new method which coupled fabric phase sorptive extraction (FPSE) with IMS for rapid detection of polycyclic aromatic hydrocarbons (PAHs) in water present in the field. Polydimethylsiloxane (PDMS) was coated on the glass fiber cloth through a sol-gel reaction. After extracting the PAHs in water, the fabric coated PDMS could be directly put into the inlet of IMS instrument for thermal desorption. The PAHs were analyzed by the IMS instrument operated in the positive ion mode with a corona discharge (CD) ionization source. The primary parameters affecting extraction efficiency such as extraction time, extraction temperature, and ionic strength were investigated and optimized by using phenanthrene (Phe), benzo[a]anthracene (BaA) and benzo[a]pyrene (BaP) as model compounds. Under the optimal conditions, the FPSE-IMS detection limits were 5 ng ml-1,8 ng ml-1 and 10 ng ml-1 respectively. Satisfactory recoveries were obtained in the range from 80.5% to 100.5% by testing the spiked real water samples and validated by the standard method（HJ487-2009）. Based on the results, the method of FPSE-IMS could be feasibly applied for monitoring the water quality on-site and providing early warning in the field.

Toxicity assessment of the extractables from multi-layer coextrusion poly ethylene bags exposed to pH=5 solution containing 4% benzyl alcohol and 0.1 M sodium acetate.

A non-target analysis was developed for the analysis of extractables from multi-layer coextrusion bags exposed to 4% benzyl alcohol solution and 0.1 M sodium acetate at pH = 5 for defined periods (15 day, 45 day and 90 day) according to manufacturer instructions based on the ultra-performance liquid chromatography (UPLC) quadrupole-time of flight mass spectrometry (Q-TOF MS). In order to confirm the extractables, principal component analysis (PCA) was used to indicate the differences among samples of different periods. Then, the extractables were identified based on searching the self-built library or online searching. The total content of extractables of 90 day samples was 589.78 µg/L, and the content was in the range of acceptable levels for pharmaceutical manufacturers. The risk assessment of the extractables were evaluated by Toxtree and T.E.S.T. software to avoid the animals bioexperiment.

Detection and Identification of Leachables in Vaccine from Plastic Packaging Materials Using UPLC-QTOF MS with Self-Built Polymer Additives Library.

The direct contact of plastic parts with the medical products raises the possibility that plastic-related contaminants (leachables) may be present in the finished medical product. The leachable components from plastic materials may impact the safety and efficacy of the final medical product, so identification and determination of the leachables are essential for the safety assessment of medical products. A method to identify main leachables-polymer additives in medical products was developed by ultraperformance liquid chromatography-quadrupole time-of-flight-mass spectrometry (UPLC-QTOF MS) and a self-built library. The library contains 174 additives and the information on their names, formulas, structures, retention times, fragments, classifications, origin, and corresponding MS(E) and MSMS spectra. The reliability of the construction process of the library was guaranteed by the system stability and suitability test. Identification parameters of library application, such as mass error, retention times, fragments, and isotope pattern, were evaluated. Leachables in real vaccine and the intermediates were identified using automatic library searching. In vaccine, the peak m/z 239.0887 that could not be assigned by the library was identified as dimethyl 2-hydroxy-1,3-cyclohexanedicarboxylate using a series of elucidation tools. As a result, the concentrations of leachables in vaccine and the intermediates ranged from 0.85 to 21.91 µg/L.