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External standard calibration method for high-repetition-rate shock tube kinetic studies with synchrotron-based time-of-flight mass spectrometry.

ABSTRACT: The signal levels observed from mass spectrometers coupled by molecular beam sampling to shock tubes are impacted by dynamic pressures in the spectrometer due to rapid pressure changes in the shock tube. Accounting for the impact of the pressure changes is essential if absolute concentrations of species are to be measured. Obtaining such a correction for spectrometers operated with vacuum ultra violet photoionization has been challenging. We present here a new external calibration method which uses VUV-photoionization of CO₂ to develop time-dependent corrections to species concentration/time profiles from which kinetic data can be extracted. The experiments were performed with the ICARE-HRRST (high repetition rate shock tube) at the DESIRS beamline of synchrotron SOLEIL. The calibration experiments were performed at temperatures and pressures behind reflected shock waves of 1376 ± 12 K and 6.6 ± 0.1 bar, respectively. Pyrolytic experiments with two aromatic species, toluene (T₅ = 1362 ± 22 K, P₅ = 6.6 ± 0.2 bar) and ethylbenzene (T₅ = 1327 ± 18 K, P₅ = 6.7 ± 0.2 bar), are analyzed to test the method. Time dependent concentrations for molecular and radical species were corrected with the new method. The resulting signals were compared with chemical kinetic simulations using a recent mechanism for pyrolytic formation of polycyclic aromatic hydrocarbons. Excellent agreement was obtained between the experimental data and simulations, without adjustment of the model, demonstrating the validity of the external calibration method.

SUBMITTER: Cano Ardila FE

PROVIDER: S-EPMC10895696 | biostudies-literature | 2024 Feb

REPOSITORIES: biostudies-literature

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External standard calibration method for high-repetition-rate shock tube kinetic studies with synchrotron-based time-of-flight mass spectrometry.

Cano Ardila Fabian E FE Nagaraju Sharath S Tranter Robert S RS Garcia Gustavo A GA Desclaux Anthony A Roque Ccacya Anthony A Chaumeix Nabiha N Comandini Andrea A

The Analyst 20240226 5

The signal levels observed from mass spectrometers coupled by molecular beam sampling to shock tubes are impacted by dynamic pressures in the spectrometer due to rapid pressure changes in the shock tube. Accounting for the impact of the pressure changes is essential if absolute concentrations of species are to be measured. Obtaining such a correction for spectrometers operated with vacuum ultra violet photoionization has been challenging. We present here a new external calibration method which u ...[more]

PMID: 38289286

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Project description:Quantitative mass spectrometry imaging (MSI) is an effective technique for determining the spatial distribution of molecules in a variety of sample types; however, the quality of the ion signals is related to the chemical and morphological properties of the tissue and the targeted analyte(s). Issues may arise with the incorporation of standards into the tissue at repeatable, well-defined concentrations, as well as with the extraction and incorporation of endogenous analytes versus standards from tissue into the matrix. To address these concerns, we combine imprint MSI (iMSI) with kinetic calibration and use it to quantify lipids in rat brain tissue samples. Briefly, tissues were imprinted on slides coated with a dopamine-modified TiO2 monolith pretreated with analyte standards, resulting in the adsorption of endogenous analytes onto the coating and desorption of standards into the tissue. The incorporation of standards into the tissue enabled quantification of the measured analytes using kinetic calibration. Moreover, matrix effects were reduced, and the intensities of analyte standard signals became more uniform. The symmetry of the adsorption of endogenous ceramides and the desorption of ceramide standards suggest that the content of adsorbed endogenous ceramide can be determined by measuring the content of desorbed ceramide standard. Using kinetic calibration, endogenous ceramide concentrations were calculated for a range of dry and wet tissue imprinting conditions and compared to quantitative MSI using a standard spiking approach. We validated the relative quantitative values from iMSI using liquid chromatography tandem mass spectrometry (LC-MS/MS) and found that the ratios from iMSI as compared to LC-MS/MS were in the range of 70-200% over the concentration range of endogenous ceramides; the correlation coefficient between iMSI and LC-MS/MS was over 0.9 (Pearson's r), while the relative recoveries via traditional standard spiking were between 200% and 5000% depending on the brain region and sample preparation conditions.

Dataset Information

External standard calibration method for high-repetition-rate shock tube kinetic studies with synchrotron-based time-of-flight mass spectrometry.

Publications

External standard calibration method for high-repetition-rate shock tube kinetic studies with synchrotron-based time-of-flight mass spectrometry.

Similar Datasets

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