Preparation of Hollow Silica Nanoparticles Using Fluorinated Surfactant and Fluorocarbon Solvents

In this study, we used a new class of fluorinated surfactant as a soft template for the preparation of the hollow silica nanoparticles. The size of the hollow silica nanoparticles was enlarged by incorporating a variety of swelling agents (perfluorodecalin, perfluorotributylamine, perfluorooctane, and perfluorooctyl bromide) into the cores of the micelles of the fluorinated surfactant. However, once we used the perfluorinated acids (perfluorooctadecanoic acid and perfluorodecanoic acid) as swelling agents, the structure of silica nanoparticles is solid without the formation of hollow voids. The TEM analysis combined with copper elemental mapping of the hollow silica loaded with copper hexadecafluorophthalocyanine indicated that the cores of the hollow silica nanoparticles are hydrophobic. The formation mechanism of the hollow silica nanoparticles is similar to that prepared by hydrocarbon surfactant/hydrocarbon, which was supported by the zeta potential measurements. The prepared hollow silica nanoparticles had the type IV isotherm with the H3 hysteresis loop.

Characterization of the mass-dependent transmission efficiency of a CIMS

Knowledge about mass discrimination effects in a chemical ionization mass spectrometer (CIMS) is crucial for quantifying, e.g., the recently discovered extremely low volatile organic compounds (ELVOCs) and other compounds for which no calibration standard exists so far. Here, we present a simple way of estimating mass discrimination effects of a nitrate-based chemical ionization atmospheric pressure interface time-of-flight (CI-APi-TOF) mass spectrometer. Characterization of the mass discrimination is achieved by adding different perfluorinated acids to the mass spectrometer in amounts sufficient to deplete the primary ions significantly. The relative transmission efficiency can then be determined by comparing the decrease of signals from the primary ions and the increase of signals from the perfluorinated acids at higher masses. This method is in use already for PTR-MS; however, its application to a CI-APi-TOF brings additional difficulties, namely clustering and fragmentation of the measured compounds, which can be treated with statistical analysis of the measured data, leading to self-consistent results. We also compare this method to a transmission estimation obtained with a setup using an electrospray ion source, a high-resolution differential mobility analyzer and an electrometer, which estimates the transmission of the instrument without the CI source. Both methods give different transmission curves, indicating non-negligible mass discrimination effects of the CI source. The absolute transmission of the instrument without the CI source was estimated with the HR-DMA method to plateau between the m∕z range of 127 and 568 Th at around 1.5 %; however, for the CI source included, the depletion method showed a steady increase in relative transmission efficiency from the m∕z range of the primary ion (mainly at 62 Th) to around 550 Th by a factor of around 5. The main advantages of the depletion method are that the instrument is used in the same operation mode as during standard measurements and no knowledge of the absolute amount of the measured substance is necessary, which results in a simple setup.

Characterization of the mass dependent transmission efficiency of a CIMS

Knowledge about mass discrimination effects in a Chemical Ionization Mass Spectrometer (CIMS) is crucial for quantifying e.g. the recently discovered Extremely Low Volatile Organic Compounds (ELVOCs) and other compounds for which no calibration standard exists so far. Here, we present a simple way of estimating mass discrimination effects of a nitrate based Chemical Ionization Atmospheric Pressure interface Time of Flight (CI-APi-TOF) mass spectrometer. Characterization of the mass discrimination is achieved by adding different perfluorinated acids to the mass spectrometer in amounts sufficient to deplete the primary ions significantly. The relative transmission efficiency can then be determined by comparing the decrease of signals from the primary ions and the increase of signals from the perfluorinated acids at higher masses. This method is in use already for PTR-MS, however its application to a CI-APi-TOF brings additional difficulties, namely clustering and fragmentation of the measured compounds, which can be treated with statistical analysis of the measured data, leading to self-consistent results. We also compare this method to a transmission estimation obtained with a setup using an Electrospray Ion source, a High Resolution Differential Mobility Analyzer and an electrometer, which estimates the transmission of the instrument without the CI source. Both methods give different transmission curves, indicating non-negligible mass discrimination effects of the CI source. The absolute transmission of the instrument without the CI source was estimated with the HR-DMA method to plateau between the m / z range of 127 and 568 Th at around 1.5 %, however for the CI source included, the depletion method showed a steady increase in relative transmission efficiency from the m / z range of the primary ion (mainly at 62 Th) to around 550 Th by a factor of around 5. The main advantages of the depletion method are that the instrument is used in the same operation mode as during standard measurements and no knowledge of the absolute amount of the measured substance is necessary, which results in a simple setup.

Material Properties for Degradation and Reduction of Perfluorinated Acid in Complex Pollution System by Photo-Induced Hydrated Electrons

F, the most electronegative element, is easy to catch the electrons in the bonds to form the stabilized C-F. Perfluorinated acids have high chemical stability which can tolerate acid, alkali, etc. Inhibition effect was observed in the complex pollution system in which 7 kinds of perfluorinated acids existed simultaneously. The formation of hydrated electrons was the rate-limiting step in complex pollution system, and the inhibition was increased as the carbon chain increasing. Compared the reduction rate of perfluorinated acids by photo-induced hydrated electrons in the complex pollution system with the single rate, the results showed that there were positive linear correlations between the degradation rate and photo-induced hydrated electrons. The degradation multiples of perfluorinated acids were studied, it concluded that, because of the competition among the 7 kinds of perfluorinated acids, the degradation rates were influenced.