Principles of Charged Aerosol Detection

Gamache, Paul H.; Kaufman, Stanley L.

doi:10.1002/9781119390725.ch1

Cited by 7 publications

(5 citation statements)

References 76 publications

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“…A technique able to unambiguously detect all nonvolatile material in a sample and achieve a near uniform response is charged aerosol detection (CAD). The detector response is independent from the physiochemical properties of the material and its signal is proportional only to the amount of material transferred to the analyzer. − This analyzer is compatible with simultaneous analysis by ESI-HRMS because of similar requirements for solvent volatility.…”

Section: Introductionmentioning

confidence: 99%

Investigating the Ionization of Dissolved Organic Matter by Electrospray

et al. 2020

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Electrospray ionization (ESI) operating in the negative mode coupled to high-resolution mass spectrometry is the most popular technique for the characterization of dissolved organic matter (DOM). The vast molecular heterogeneity and the functional group diversity of this complex mixture prevents the efficient ionization of the organic material by a single ionization source, so the presence of uncharacterized material is unavoidable. The extent of this poorly ionizable pool of carbon is unknown, is presumably variable between samples, and can only be assessed by the combination of analysis with a uniform detection method. Charged aerosol detection (CAD), whose response is proportional to the amount of nonvolatile material and is independent from the physicochemical properties of the analytes, is a suitable candidate. In this study, a fulvic acid mixture was fractionated and analyzed by high-pressure liquid chromatography–mass spectrometry in order to investigate the polarity and size distributions of highly and poorly ionizable material in the sample. Additionally, DOM samples of terrestrial and marine origins were analyzed to evaluate the variability of these pools across the land–sea aquatic continuum. The relative response factor values indicated that highly ionizable components of aquatic DOM mixtures are more hydrophilic and have lower molecular weight than poorly ionizable components. Additionally, a discrepancy between the samples of terrestrial and marine origins was found, indicating that marine samples are better represented by ESI than terrestrial samples, which have an abundant portion of hydrophobic poorly ionizable material.

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Section: Introductionmentioning

confidence: 99%

Investigating the Ionization of Dissolved Organic Matter by Electrospray

et al. 2020

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“…Due to the specificity of the CAD, the acquired signal only shows linearity in a narrow concentration range [ 39 ]. With the widened range, the relationship between the response and the concentrations is always curvilinear; thus, a quadratic, logarithmic or power fit is usually applicable [ 34 , 40 , 41 , 42 ]. In the current study, the following transformation was applied:

where: A —normalized peak area; X —power function value; scale —full-scale range of the detector (e.g., 500 pA); A lin —response value eligible for linear fit calibration.…”

Section: Resultsmentioning

confidence: 99%

Determination of Glycerophospholipids in Biological Material Using High-Performance Liquid Chromatography with Charged Aerosol Detector HPLC-CAD—A New Approach for Isolation and Quantification

2022

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The method of using high-performance liquid chromatography with a charged aerosol detector method (HPLC-CAD) was developed for the separation and determination of phospholipids isolated from cell membranes. The established cell lines—normal and neoplastic prostate cells and normal skin fibroblasts and melanoma cells—were selected for the study. Chromatographic separation was performed in the diol stationary phase using a gradient elution based on a mixture of n-hexane, isopropanol and water with the addition of triethylamine and acetic acid as buffer additives. Taking the elements of the Folch and Bligh–Dyer methods, an improved procedure for lipid isolation from biological material was devised. Ultrasound-assisted extraction included three extraction steps and changed the composition of the extraction solvent, which led to higher recovery of the tested phospholipids. This method was validated by assessing the analytical range, precision, intermediate precision and accuracy. The analytical range was adjusted to the expected concentrations in cell extracts of various origins (from 40 µg/mL for PS up to 10 mg/mL for PC). Both precision and intermediate precision were at a similar level and ranged from 3.5% to 9.0%. The recovery for all determined phospholipids was found to be between 95% and 110%. The robustness of the method in terms of the use of equivalent columns was also confirmed. Due to the curvilinear response of CAD, the quantification was based on an internal standard method combined with a power function transformation of the normalized peak areas, allowing the linearization of the signal with an R2 greater than 0.996. The developed method was applied for the isolation and determination of glycerophospholipids from cell membranes, showing that the profile of the tested substances was characteristic of various types of cells. This method can be used to assess changes in metabolism between normal cells and neoplastic cells or cells with certain pathologies or genetic changes.

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“…The TEA was selected due to its volatility which makes it a good choice for CAD detection. 23,42 It also improves the peak shapes of cationic lipids possessing amine groups that may protonate under acidic conditions. 23 It is noteworthy that cationic lipids are becoming increasingly relevant in liposomal formulations for vaccines.…”

Section: Column and Mobile Phase Selectionmentioning

confidence: 99%

Digitally Enabled Generic Analytical Framework Accelerating the Pace of Liquid Chromatography Method Development for Vaccine Adjuvant Formulations

Hemida,

Barrientos,

Kinsey

et al. 2024

Preprint

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The growing use of adjuvants in the fast-paced formulation of new vaccines has created an unprecedented need for meaningful analytical assays that deliver reliable quantitative data from complex adjuvant and adjuvant-antigen mixtures. Due to their complex chemical and physical properties, method development for the separation of vaccine adjuvants is considered a highly challenging and laborious task. Reversed-phase liquid chromatography (RPLC) is among the most important tests in the (bio)pharmaceutical industry for release and stability indicating measurements including adjuvant content, identity, and purity profile. However, the time constraints of developing “on-demand” robust quantitative methods prior to each change in formulation can easily lead to sample analysis becoming a bottleneck in vaccine development. Herein a simple and efficient generic analytical framework capable of chromatographically resolving the most commonly used non-aluminum based adjuvants across academic and industrial sectors is introduced. This was designed to seek a more proactive approach for fast-paced assay development endeavors that evolved from extensive stationary phase screening in conjunction with multifactorial in silico simulations of adjuvant retention time (RT) as a function of gradient time, temperature, organic modifier blending, and buffer concentration. The multifactorial retention models yield 3D resolution maps with excellent baseline separation of all adjuvants in a single run, which was found to be very accurate, with differences between experimental and simulated retention times of less than 1%. The analytical framework described here also includes the introduction of a more versatile approach to method development by introducing a dynamic RT database for adjuvants covering the entire library of adjuvants with broad mechanisms of action across numerous vaccine formulations with excellent linearity, accuracy, precision, and specificity. The power of this framework was also demonstrated with numerous analytical assays that can be generated rapidly from simulations guiding vaccine processes in the development of new adjuvant formulations. Analytical assay in this work covers content, purity profile by RPLC-UV-CAD, and component identification (RPLC-MS) across complex vaccine formulations, including the use of surfactants (e.g., polysorbates), as well as their separation from adjuvant targets.

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Principles of Charged Aerosol Detection

Cited by 7 publications

References 76 publications

Investigating the Ionization of Dissolved Organic Matter by Electrospray

Investigating the Ionization of Dissolved Organic Matter by Electrospray

Determination of Glycerophospholipids in Biological Material Using High-Performance Liquid Chromatography with Charged Aerosol Detector HPLC-CAD—A New Approach for Isolation and Quantification

Digitally Enabled Generic Analytical Framework Accelerating the Pace of Liquid Chromatography Method Development for Vaccine Adjuvant Formulations

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