Charged Aerosol Research Articles

Carbon Dioxide Microbubble Bursting Ionization Mass Spectrometry.

Aerosols generated by bubble bursting have been proved to promote the extraction of analytes and have ultrahigh electric fields at their water-air interfaces. This study presented a simple and efficient ionization method, carbon dioxide microbubble bursting ionization (CDMBI), without the presence of an exogenous electric field (namely, zero voltage), by simulating the interfacial chemistries of sea spray aerosols. In CDMBI, microbubbles are generated in situ by continuous input of carbon dioxide into an aqueous solution containing low-concentration analytes. The microbubbles extract low- and high-polarity analytes as they pass through the aqueous solution. Upon reaching the water-air interface, these microbubbles burst to produce charged aerosol microdroplets with an average diameter of 260 μm (8.1-10.4 nL in volume), which are immediately transferred to a mass spectrometer for the detection and identification of extracted analytes. The above analytical process occurs every 4.2 s with a stable total ion chromatogram (relative standard deviation: 9.4%) recorded. CDMBI mass spectrometry (CDMBI-MS) can detect surface-active organic compounds in aerosol microdroplets, such as perfluorooctanoic acid, free fatty acids epoxidized by bubble bursting, sterols, and lecithins in soybean and egg, with the limit of detection reaching the level of fg/mL. In addition, coupling CDMBI-MS with an exogenous voltage yields relatively weak gains in ionization efficiency and sensitivity of analysis. The results suggested that CDMBI can simultaneously accomplish both bubbling extraction and microbubble bursting ionization. The mechanism of CDMBI involves bubbling extraction, proton transfer, inlet ionization, and electrospray-like ionization. Overall, CDMBI-MS can work in both positive and negative ion modes without necessarily needing an exogenous high electric field for ionization and quickly detect trace surface-active analytes in aqueous solutions.

Establishment of SI-traceable purity assessment of Fumonisin B1 using a combination of quantitative 1H NMR and mass balance

The accurate purity assessment of Fumonisin B1 (FB1) is of great challenge due to the lack of inherent chromophore, which is important for the development of FB1 certified reference material. In this study, differential scanning calorimetry (DSC), mass balance and quantitative 1H nuclear magnetic resonance (qH NMR) methods were developed and validated for international system of unit (SI) traceable purity assessment of in-house prepared FB1. The thermodynamic analysis showed no typical melting peak was observed for FB1, indicating DSC was not applicable for purity assessment of FB1. A high-performance liquid chromatography coupled with corona charged aerosol detector (HPLC-CAD) method was developed and an isocratic elution procedure was optimized for the chromatographic purity analysis of FB1. The linear range of optimized HPLC-CAD method could not cover the concentration range of FB1 and the structure-related impurity in the raw material, which was identified to be partial hydrolyzed FB1 (pHFB1). The correction factor used to correct the chromatographic purity obtained by area normalization method was approximately 0.2 %. Moisture (0.30 %) and pHFB1 (0.48 %) were the main impurities according to the mass balance analysis. A mixture of dimethyl sulfoxide-d6 and trifluoroacetic acid-d was confirmed to be a suitable deuterated solvent for accurate qH NMR analysis of FB1. The purity obtained by mass balance (99.13 % with uncertainty of 0.06 %) and qH NMR (99.12 % with uncertainty of 0.28 %) showed good consistency and equivalent precision. These methods are expected to be applicable to development of FB1 certified reference material with metrological traceability to the SI unit to ensure comparable and reliable detection results.

Three-dimensional nanoprinting with charged aerosol focusing via an electrified mask

Three-dimensional (3D) nanoprinting techniques attract significant research interest due to their capacity to manufacture diverse structures. The techniques enhance the performance of various applications by realizing unique functionalities from the size and geometrical effects of small-scale 3D structures. A recently reported 3D nanoprinting technique that utilizes charged aerosol jets generated by ion accumulation on the dielectric mask as a printing tool is promising for enabling parallel intricate 3D nanostructures in atmospheric conditions. In this technique, modulating the voxel size of the printed structure was difficult because the ion accumulation that was necessary for the generation of converged aerosol jets was not easy to be controlled. Here, we demonstrate a charged aerosol jet-based advanced 3D nanoprinting technique that enables the programming of the voxel size of 3D nanostructures by replacing the ion accumulated dielectric mask with the electrified mask. The electrified mask readily controls the local electric field strength between the mask and conducting substrate, which influences the diameter of charged aerosol jets and thus determines the voxel size of the 3D nanostructures. By additionally controlling the distance between the mask and substrate and changing the hole size of the mask, we show that the voxel size can be further altered. Moreover, moving the substrate in three-dimensions prints desired shapes of the 3D nanostructures, such as overhanging structures and helices with controlled voxel sizes. In addition, we present theoretical approaches to predict the geometries and voxel sizes of 3D nanostructures.

Development of Medical Sensor Systems in Pulmonology Based on Electrical Impedance Measurement.

In order to experimentally confirm the dependence of the bioelectrical impedance on the flow rate of charged aerosol particles and the composition of bronchial secretions in small airways, the electrical impedance of an aerosol of 0.9% NaCl solution in polyethylene tubes of various diameters was studied. The electrical impedance was also measured in cylindrical chambers of various diameters and volumes filled with a 0.9% NaCl solution or a gelatin solution. The studies were carried out at frequencies of alternating electric current from 20 Hz to 150 kHz. It was shown that the electrical current is not recorded in the absence of a flow of aerosol particles, and the impedance decreases with an increase in the flow velocity. The impedance modulus and the phase angle of the electrical impedance has an expressed dependence on the composition of the conductive medium, the impedance modulus increases in the gelatin solution medium, with a decrease in the diameter of the electric current conductor, and decreases with an increase in the frequency of the probing alternating current. The obtained results confirmed the hypothesis about the influence of the speed of salty aerosol particles flow and the composition of bronchial secretions on the results of measuring electrical impedance.

Differentiating root and rhizome of panax notoginseng based on precursor ion scanning and multi heart-cutting two-dimensional liquid chromatography.

Owing to increasing demand for Panax notoginseng-based medicines and health products, establishing a fast, simple, and reliable assay to analyze the chemical differences between its root and rhizome is important. Although previous studies showed that the chemical and biological differences between the root and rhizome of P. notoginseng seem to be small, efforts should be taken to investigate such differences to ensure the safety and efficacy of the products. This work describes a holistic approach that combines characteristic fingerprinting using ultra-high performance liquid chromatography-tandem mass spectrometry parent ion scanning with charged aerosol detection and targeted separation by online heart-cutting two-dimensional liquid chromatography, to identify and evaluate characteristic markers allowing differentiation of the root and rhizome. A total of five potential markers chikusetsusaponin L5 , ginsenoside Rb2 , stipuleanoside R2, malonyl-ginsenoside Rb1 , and malonyl-ginsenoside Rd, were identified and confirmed by comparing chromatographic retention time, the accurate mass of molecular weight, and the fragments of secondary MS with the available reference materials. The results showed that all five markers were 2.8-7 times higher in content in the rhizome than in the root.

Measurement of the rate coefficients between atmospheric ions and multiply charged aerosol particles in the CERN CLOUD chamber

Measurement of the rate coefficients between atmospheric ions and multiply charged aerosol particles in the CERN CLOUD chamber

Effect of Oily Aerosol Charge Characteristics on the Filtration Efficiency of an Electrostatically Enhanced Fibrous Filter System

The synergistic effect of electrostatically enhanced fibrous filtration originates from the charging characteristics of aerosol particles and electret fibers in an electric field. Two electrostatically enhanced fibrous filter systems are designed in this study to investigate the mechanism of the effects of the charging characteristics of oily aerosol on the filtration efficiency. We investigate the charging characteristics and their effects on the filtration efficiency of dioctyl-phthalate (DOP) aerosol particles of various sizes by setting different filter systems and electric field intensities. The experimental results show that the charge of DOP particles increases with the strength of the electric field, and the average charge increases with the particle size. The maximum charge of DOP particles reaches 4760 eC/P, and the filtration efficiency of the coupled system improves when DOP particles are amply charged. For 0.25 μm DOP particles as the most penetrating particle size, the system had good long-term stability, and the filtration efficiency is approximately 72% higher than that of the fiber acting alone. Meanwhile, the problem of oily aerosol deposition reducing the electret filtration efficiency is solved, providing a basis for long-term filtration and oily aerosol purification by electret fiber.

Development of a novel, label-free N-glycan method using charged aerosol detection

Monoclonal antibodies (mAbs) are complex glycoproteins that are developed for treatment of various therapeutic indications such as cancer and autoimmune diseases. MAbs are glycosylated at conserved asparagine residues (N-X-S/T) of the Fc region at amino acid position 297 of the heavy chain. Glycans are important in governing the functions of efficacy and serum half-life of protein therapeutics and are part of the critical quality attribute panel for release testing. Traditionally, N-linked glycans are released from glycoproteins after denaturation and enzymatic digestion with PNGase F, followed by fluorescent labeling of the liberated glycans. The labeled glycans are then separated using hydrophilic liquid chromatography (HILIC) with fluorescence detection to generate chromatographic profile. Despite decades of use, this strenuous process remains unchanged, utilizing toxic reagents and extended sample preparation time. As an intervention, this report showcases a novel, label-free approach to detect and quantify N-glycans without using fluorescent labeling. Separation of glycans using mixed-mode PGC column along with detection of non-derivatized glycans using charged aerosol detector, the overall turnaround time can be greatly reduced with significant cost savings. The label-free method provides similar quantitative results as the conventional fluorescent labeled method, confirming the validity of the method for product release.

Preventing Aerosol Emissions in a CO2 Capture System: Combining Aerosol Formation Inhibition and Wet Electrostatic Precipitation.

Aerosol emission from the CO2 capture system has raised great concern for causing solvent loss and serious environmental issues. Here, we propose a comprehensive method for reducing aerosol emissions in a CO2 capture system under the synergy of aerosol formation inhibition and wet electrostatic precipitation. The gas-solvent temperature difference plays a vital role in aerosol formation, with aerosol emissions of 740.80 mg/m3 at 50 K and 119.36 mg/m3 at 0 K. Different effects of SO2 and SO3 on aerosol formation are also found in this research; the aerosol mass concentration could reach 2341.25 mg/m3 at 20 ppm SO3 and 681.01 mg/m3 at 50 ppm SO2 with different aerosol size distributions. After the CO2 capture process, an aerosol removal efficiency of 98% can be realized by electrostatic precipitation under different CO2 concentrations. Due to the high concentration of aerosols and aerosol space charge generated by SO2 and SO3, the removal performance of the wet electrostatic precipitator decreases, resulting in a high aerosol emission concentration (up to 130.26 mg/m3). Thus, a heat exchanger is installed before the electrostatic precipitation section to enhance aerosol growth and increase aerosol removal efficiency. Under the synergy of aerosol formation inhibition and electrostatic precipitation, an aerosol removal efficiency of 99% and emission concentrations lower than 5 mg/m3 are achieved, contributing to global warming mitigation and environmental protection.

Quantitative nuclear magnetic resonanceof chloride by an accurate internal standard approach.

Chloride is the most common counterion used to improve aqueous solubility and enhance stability of small molecule active pharmaceutical ingredients. While several analytical techniques, such as titration, HPLC with charged aerosol detection, and ion chromatography, are currently utilized to assay the level of chloride, they have notable limitations, and these instruments may not be readily available. Here, we present a generally applicable 35 Cl solution NMR method to assay the level of chloride in pharmaceutical compounds. The method uses KClO4 as an internal standard for improved accuracy in comparison with external standard methods, and it was found to be robust, linear over three orders of magnitude, precise (<3% RSD), and accurate (<0.5% absolute error).

Determination of related substances in egg yolk lecithin by HPLC-CAD and characterization of its profiling by HPLC-Q-TOF-MS

A high-performance liquid chromatography (HPLC) method has been developed for the determination of related substances in egg yolk lecithin. Chromatographic separation was achieved using a gradient elution on a Waters Xbridge HILIC column maintained at 35 ℃. Mobile phase A was composed of water-acetonitrile (80:20, v/v, containing 5 mM ammonium acetate), and mobile phase B was composed of acetonitrile. Analytes were monitored by a charged aerosol detector (CAD) at 50 ℃. The novel HPLC-CAD method was selective and sensitive for the determination of related substances in egg yolk lecithin in its commercial bulk batches. It was also successfully validated by the International Council for Harmonisation (ICH) guidelines. The method will be a renewal of an old Chinese Pharmacopoeia method (2020 edition). Moreover, quadrupole time-of-flight mass spectrometry (Q-TOF-MS) was integrated with HPLC to investigate phospholipid species in egg yolk lecithin. This work provides comprehensive composition profiles of egg yolk lecithin, thereby accelerating the quality control, development, and application of egg yolk lecithin.

Particle beam deflection imaging for simultaneous characterization of aerosol particle size and charge

We present a novel method referred to as Particle Beam Deflection Imaging (PBDI) for the simultaneous characterization of the size and electric charge distribution of submicrometer (currently ∼200–800 nm) aerosol particles in real-time (currently ≤30 s). It combines aerodynamic and electrostatic particle deflection, providing two-dimensional information on size and charge in a single two-dimensional light scattering image. The image allows one to extract information on charge-averaged and charged-resolved particle size distributions, and on size-dependent bipolar charge distributions. The current prototype has a size resolution of <50 nm and can resolve individual charge states. Compared to Scanning Mobility Particles Sizers (SMPS), the PBDI offers the advantage of providing simultaneous size and charge information at higher size resolution in a significantly shorter measurement time, hence allowing real-time characterization of volatile aerosol particles.

Alternative methods to assess the impurity profile of a monographed API using acarbose as an example

Even though the impurity analysis of the Ph. Eur. is considered well-studied, its methodology should be reviewed periodically to ensure that it is working properly, and all impurities are captured by the section „Related substances” of the monograph. Within this study, the biotechnological produced antidiabetic drug acarbose was chosen to demonstrate some of the advantages as well as the shortcomings arising from the current related substances test of acarbose. Due to its weak chromophore, acarbose is studied by UV detection at 210 nm after being separated on aminopropyl-silyl stationary phases. Thus, the use of alternative detection techniques, such as charge aerosol detection (CAD) and a volatile mobile phase can be beneficial here. Since a simple method transfer to a mobile phase usable with the CAD was not possible, more stable stationary phases were tested. For the rapid determination of the sum of impurities, a method was developed using a pentafluorophenyl column and a mobile phase of 0.1% TFA in water. Maltose and maltotriose were further identified as additional impurities of the API. Furthermore, a method was developed and validated by means of an Amide-HILIC phase, that adequately separated acarbose and all of its impurities. However, the sensitivity of this method needs to be further improved. Additionally, a method was also developed and validated, taking into account the temperature stability of graphite columns. Thus, the separation was carried out at temperatures of about 90 °C to solve the problem of anomerization of acarbose and some of its impurities. In comparison with the other developed methods, the elution order was changed and has to be confirmed, but all components were separated and detected at a sufficient LOQ of 0.10%.

Determination of gypenoside XLVI and LVI in Gynostemma pentaphyllum from Fujian by ultra-high performance liquid chromatography-charged aerosol detector

该研究利用超高效液相色谱-电雾式检测器(UHPLC-CAD)建立了福建产绞股蓝中绞股蓝皂苷XLVI和LVI含量的测定方法。首先利用超高效液相色谱-四极杆-飞行时间质谱(UHPLC-Q-TOF/MS)结合UHPLC-CAD鉴定了福建产绞股蓝的主要成分,其中绞股蓝皂苷XLVI、LVI以及二者相应的含丙二酰基酸性皂苷为其主成分,因此在含量测定时先进行碱水解预处理将酸性皂苷转化为对应的去丙二酰基中性皂苷,再利用UHPLC-CAD测定碱水解后绞股蓝皂苷XLVI和LVI的含量。将绞股蓝样品粉末在乙醇-水-氨水(50∶46∶4, v/v/v)和料液比1∶150(g∶mL)条件下超声提取30 min,静置24 h后,在Waters ACQUITY UPLC BEH C18色谱柱(100 mm×2.1 mm, 1.7 μm)上分离,采用0.1%(v/v)甲酸水溶液和乙腈作为流动相进行梯度洗脱,流速0.5 mL/min,柱温40 ℃,电雾式检测器检测。结果表明,绞股蓝皂苷XLVI和LVI分别在9.94~318.00 μg/mL和12.78~409.00 μg/mL范围内具有良好的线性关系,相关系数(r)分别为0.9993和0.9995。方法精密度、重复性和24 h稳定性试验的相对标准偏差(RSD)均小于2.0%(n=6),绞股蓝皂苷XLVI与LVI的加标回收率分别在100.2%~107.2%与97.9%~104.2%范围内,RSD值分别为2.4%与2.6%。16批绞股蓝样品含量测定结果显示:绞股蓝皂苷XLVI含量占0.57%~2.57%,绞股蓝皂苷LVI含量占0.66%~2.99%。该方法灵敏度高,重复性好,可用于福建产绞股蓝的质量研究和质量控制。

Study on Integrated Pharmacokinetics of the Component-Based Chinese Medicine of Ginkgo biloba Leaves Based on Nanocrystalline Solid Dispersion Technology

BackgroundTo improve the dissolution and bioavailability of the component-based Chinese medicine of Ginkgo biloba leaves (GBCCM), a novel nanocrystalline solid dispersion of GBCCM (GBCCM NC-SD) was first prepared.MethodsGBCCM mainly containing high pure flavonoid aglycones (FAs) and terpenoid lactones (TLs) was used as the model drug. PVP K30 and SDS were used as solubilizers, combined stabilizers and carriers, and GBCCM NC-SD was prepared by high-pressure homogenization combined with freeze-dryer. Morphology and crystal characteristic of GBCCM NC-SD were analyzed. The dissolution and bioavailability evaluation were performed to investigate the feasibility of GBCCM NC-SD by in vitro dissolution and in vivo integrated pharmacokinetic models.ResultsAfter homogenizing for 30 cycles under the pressure of 650 bar and freeze-drying, GBCCM NC-SD with uniform quality would be obtained. The particle size, PDI and zeta potential were found to be 335.9 ± 32.8 nm, 0.29 ± 0.02 and −28.4 ± 0.7 mV respectively. Based on charged aerosol detector (CAD) technology, a new chromatographic method for simultaneous detection of eight components in GBCCM was developed. In vitro drug release study showed that the cumulative dissolution of FAs and TLs in GBCCM NC-SD increased from 12.77% to 52.92% (P < 0.01) and 90.91% to 99.21% (P < 0.05) respectively. In comparison with physical mixture of GBCCM and stabilizer (PM), the integrated pharmacokinetics AUC0-t of FAs and TLs in GBCCM NC-SD were significantly increased (P < 0.05), and the T1/2 of TLs was also significantly prolonged (P < 0.05).ConclusionThis study demonstrated that novel GBCCM NC-SD was prepared using Polyvinylpyrrolidone K30 (PVP K30) and Sodium dodecyl sulfate (SDS) as a synergetic stabilizer and also provided a feasible way to improve the dissolution and oral bioavailability of poorly soluble candidate antihypertensive drugs.

Elemental analysis of single ambient aerosol particles using laser-induced breakdown spectroscopy

Analysing the composition of aerosol particles is essential when studying their health effects, sources and atmospheric impacts. In many environments the relevant particles occur in very low concentrations, meaning that their analysis requires efficient single particle techniques. Here we introduce a novel method to analyse the elemental composition of single aerosol particles sampled directly from the aerosol phase using size amplification aided aerosol charging (SAAC), linear electrodynamic quadrupole (LEQ) and laser-induced breakdown spectroscopy. We present results of the charging and focusing efficiencies of the SAAC and of the LEQ, and a proof-of-concept of the analysis method. The proof-of-concept test series was conducted with particle diameters down to 300 nm, sampled directly from the aerosol phase. The method shows unprecedented performance for spectroscopic submicron particle analysis from arbitrarily low concentrations and has exceptional potential for a portable analysis platform for various applications in the field of aerosol research.

A direct and facile simultaneous quantification of non-polar and polar lipids in different species of marine samples using normal-phase HPLC–CAD

This study aimed to develop a sensitive and reliable normal-phase high-performance liquid chromatography–charged aerosol detector (NP-HPLC–CAD) method for direct and simultaneous quantification of diverse and complex lipid classes in marine samples. The 33-minute HPLC method so developed effectively separates 10 classes of non-polar and polar lipid. The quantitative calibration curves for all 10 lipid classes were built with satisfactory correlation coefficients (R2 ≥ 0.9910), wide linear range (0.01–5.00 mg/mL), low limit of detection (LOD, 2–40 ng) and limit of quantification (LOQ, 4–80 ng). The precision (relative standard deviation of 2.33–7.13 %) and recovery rate (83.69–108.06 %) for the quantitative method met the acceptance criteria of FDA guidelines. Finally, the NP-HPLC–CAD method was successfully used to analyze marine lipid samples from abalone, oyster, scallop, mussel and Antarctic krill. Results show complex lipid composition of marine samples, mainly containing triacylglycerol, phosphatidylethanolamine and phosphatidylcholine.

Prediction of polyester conductive filter media life on flat and pilot filtration test rigs under flyash aerosol pre-charge

One of the vital aspects considering the commercial benefit for any gaseous filtration industry is the life cycle of filter material. A filter media providing consistent filtration for a long period of time is desirable for its prolonged life. In view of this; the present study is undertaken for experimental characterization of three different polyester conductive filter materials viz. PTFE coated media, stainless steel fibre blended with PET media, and stainless steel fibre scrim media by predicting their ageing behavior. The materials were investigated on two different laboratory based test rigs viz. flat based and pilot filter unit under two levels of dust densities (50 g/m3 and 150 g/m3) using fly ash aerosol. The aerosol was charged through a pre-charger at three levels viz. 4 kV, 8 kV and 12 kV. The outcome revealed an enhanced ageing performance at higher level of aerosol charge in case of both the test rigs for all the materials. However, the relative performance of the flat media test rig has been found to be better under all operating conditions. The ageing behavior of PTFE coated materials has been found to be the best among all the investigated materials in both test rigs due to its better surface characteristics as a result of coating.

Authentication of Shenqi Fuzheng Injection via UPLC-Coupled Ion Mobility-Mass Spectrometry and Chemometrics with Kendrick Mass Defect Filter Data Mining.

Nearly 5% of the Shenqi Fuzheng Injection’s dry weight comes from the secondary metabolites of Radix codonopsis and Radix astragali. However, the chemical composition of these metabolites is still vague, which hinders the authentication of Shenqi Fuzheng Injection (SFI). Ultra-high performance liquid chromatography with a charged aerosol detector was used to achieve the profiling of these secondary metabolites in SFI in a single chromatogram. The chemical information in the chromatographic profile was characterized by ion mobility and high-resolution mass spectrometry. Polygonal mass defect filtering (PMDF) combined with Kendrick mass defect filtering (KMDF) was performed to screen potential secondary metabolites. A total of 223 secondary metabolites were characterized from the SFI fingerprints, including 58 flavonoids, 71 saponins, 50 alkaloids, 30 polyene and polycynes, and 14 other compounds. Among them, 106 components, mainly flavonoids and saponins, are contributed by Radix astragali, while 54 components, mainly alkaloids and polyene and polycynes, are contributed by Radix codonopsis, with 33 components coming from both herbs. There were 64 components characterized using the KMDF method, which increased the number of characterized components in SFI by 28.70%. This study provides a solid foundation for the authentification of SFIs and the analysis of its chemical composition.

Dynamics of charged aerosols relevant to transmission of airborne infections

A simple model including the effects of initial velocity, air drag, gravity, and electrostatics on the dynamics of airborne droplets emitted from humans is presented. It is found that relatively large droplets can also travel far if their charge and/or the atmospheric electric field is sufficiently large.