Article
Spectroscopy
Sunil P. Badal, Paul B. Farnsworth, George C-Y Chan, Brian T. Molnar, Jessica R. Hellinger, Jacob T. Shelley
Summary: Plasma-based ambient desorption/ionization sources often use helium as the primary discharge gas, but studies show advantages of mixed-gas plasmas. Adding H-2 to helium can decrease reagent-ion signals while preserving analyte-ion signals. Nitrogen addition increases negative reagent ions for enhanced ion signal of specific compounds. Various molecular gases impact emission characteristics and plasma parameters in mixed-gas systems.
SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY
(2021)
Article
Chemistry, Analytical
Maureen Oliva, Dong Zhang, Paola Prada-Tiedemann, Gerardo Gamez
Summary: Flowing atmospheric pressure afterglow (FAPA) mass spectrometry is a cost-effective and potentially portable technique that allows direct desorption/ionization from samples with little-to-no sample preparation. Laser assisted sampling (LAS) is developed to address limitations with analytes of low desorption efficiency, extending the range of chemical information obtainable from polymer samples. The combination of direct desorption FAPA and LAS FAPA techniques provides a competitive advantage over conventional techniques in forensic applications.
Article
Biochemical Research Methods
Maximilian Heide, Cristian C. Escobar-Carranza, Carsten Engelhard
Summary: Ambient desorption/ionization mass spectrometry (ADI-MS) is a rapid screening tool that allows the analysis of samples without sample preparation. However, quantitative analysis of analytes in complex matrices remains a challenge. In this study, a carefully selected surface and co-deposited isotopically labeled standards were found to significantly improve the capabilities of FAPA-HR-MS for direct quantitative analysis. The use of TLC-based surfaces as sample carriers was shown to be an attractive tool for fast and efficient mass spectrometric investigations of complex samples.
ANALYTICAL AND BIOANALYTICAL CHEMISTRY
(2022)
Article
Instruments & Instrumentation
Maximilian Heide, Carsten Engelhard
Summary: Using a flowing atmospheric-pressure afterglow (FAPA) source to probe analytes on tailored thin-layer chromatography (TLC) plates enhances signal and improves quantification capabilities in plasma-based ambient desorption/ionization mass spectrometry (ADI-MS). Quantitative results can be achieved by using the TLC plate as a sampling plate without a preceding separation step. Modified dimethyl (RP2) and cyano (CN) silica TLC materials showed superior performance compared to other TLC materials.
APPLIED SPECTROSCOPY
(2023)
Article
Chemistry, Analytical
Christopher P. Rueger, Anika Neumann, Martin Sklorz, Ralf Zimmermann
Summary: APSPLI technique utilizing a fluorine excimer laser allows for selective ionization of semi- to nonpolar compounds like PAH. Installation of water and oxygen filter cartridges significantly reduces unwanted oxidized ionization artifacts, providing a new potential for analyzing complex mixtures.
ANALYTICAL CHEMISTRY
(2021)
Article
Biochemical Research Methods
Mohsen Latif, Xi Chen, Viraj D. Gandhi, Carlos Larriba-Andaluz, Gerardo Gamez
Summary: In this work, a field-switching technique combined with a flowing atmospheric pressure afterglow source was used to enhance drift tube ion mobility spectrometry. By substituting the Bradbury-Nielsen gate with a tip-repeller electrode, the performance of the ion mobility spectra was optimized and the limit of detection was significantly improved. Various operating conditions were optimized and compared with literature results.
JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY
(2022)
Article
Chemistry, Analytical
Mohsen Latif, Dong Zhang, Gerardo Gamez
Summary: This work presents the coupling of FAPA with stand-alone DTIMS for the first time, overcoming opposing potentials at the interface to study the signal of selected analytes. The spectra obtained from FAPA-DTIMS agree with literature values, showing good quantitative characterization for the selected compounds.
ANALYTICA CHIMICA ACTA
(2021)
Article
Chemistry, Analytical
Dong Zhang, David Zeldes, Gerardo Gamez
Summary: In this study, a novel diode laser-assisted micro-pyrolysis program (LAMP) technique was demonstrated to profile polymers and polymer additives in real time. Laser power modulation allowed thermal separation of additives and different pyrolysis products, and real-time duty cycle changes enabled faster temperature control. MS imaging with lateral and depth resolution was also demonstrated.
ANALYTICAL CHEMISTRY
(2022)
Article
Chemistry, Analytical
Shane R. Ellis, Jesse A. Michael, Shadrack M. Mutuku, Boris Ucur, Tassiani Sarretto, Alan T. Maccarone, Marcel Niehaus, Adam J. Trevitt
Summary: This study reports the development and optimization of a mass spectrometry imaging platform that combines atmospheric-pressure matrix-assisted laser desorption/ionization (AP-MALDI) with plasma postionization and trapped ion mobility spectrometry (TIMS). The researchers discuss optimal parameters for operating the source and characterize the behavior of different lipid classes. They also show the capabilities of the system for lipid imaging using murine brain tissue.
ANALYTICAL CHEMISTRY
(2022)
Article
Chemistry, Analytical
Jesse A. Michael, Shadrack M. Mutuku, Boris Ucur, Tassiani Sarretto, Alan T. Maccarone, Marcel Niehaus, Adam J. Trevitt, Shane R. Ellis
Summary: This study presents the development and optimization of a mass spectrometry imaging (MSI) platform that combines an atmospheric-pressure matrix-assisted laser desorption/ionization platform with plasma postionization (AP-MALDI-PPI) and trapped ion mobility spectrometry (TIMS). The platform demonstrates high sensitivity and resolution for lipid species, enabling lipid imaging in murine brain tissue. The coupling of plasma-based postionization with ion mobility allows for the resolution and identification of isobaric/isomeric lipid species that are not distinguished solely based on their mass-to-charge ratio (m/z).
ANALYTICAL CHEMISTRY
(2022)
Article
Physics, Applied
Shou-Zhe Li, Shi-Hui Xie, Yu-Long Niu, Zilu Zhao, Dezheng Yang, Jialiang Zhang, Wenchun Wang, Xuechen Li
Summary: In this study, H2S is decomposed using a N-2 microwave plasma torch, resulting in the production of hydrogen and elemental sulfur. The conversion rate of H2S into H-2 is investigated by varying the dilution ratios of H2S to N-2, MW power, total flow rate, and arrangement of cooling rods in the reaction chamber. It is found that introducing a cooling rod downstream in the reaction chamber enhances the conversion rate, and an optimum point is determined for each conversion curve based on MW power, gas flow rate, and relative distance of the cooling rod.
JOURNAL OF PHYSICS D-APPLIED PHYSICS
(2023)
Article
Physics, Fluids & Plasmas
Naoki Shirai, Hiroki Owada, Koichi Sasaki
Summary: An efficient method for generating OH radicals in the spatial afterglow of atmospheric-pressure plasma was investigated, which utilized intersecting helium flows and a DC glow discharge, with water vapor admixed at the intersection point for OH radicals formation and transportation to the afterglow zone.
PLASMA SOURCES SCIENCE & TECHNOLOGY
(2021)
Article
Spectroscopy
Huace Wu, Ding Wu, Cong Li, Longfei Li, Xue Bai, Xiaohan Hu, Zhonglin He, Yan Lyu, Ran Hai, Hongbin Ding
Summary: Real-time acquisition of dynamic information on the surface elemental composition of the first wall is crucial for understanding plasma-wall interaction and optimizing experimental conditions in a tokamak. The effect of laser ablation angles (LAAs) on the in-situ laser-induced breakdown spectroscopy (LIBS) system on the EAST upper divertor was evaluated. LIBS experiments were conducted with variable LAAs on tungsten, molybdenum, and copper samples, and their ablation depth and mass were measured. The results showed that larger LAAs improved the depth resolution of LIBS and provided valuable insights for depth-profiling analysis.
SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY
(2023)
Article
Chemistry, Analytical
Sebastian van Wasen, Yi You, Sebastian Beck, Jens Riedel, Dietrich A. Volmer
Summary: The composition of acoustically levitated droplets was investigated using a combination of mid-IR laser evaporation and subsequent postionization via secondary electrospray ionization. It was found that the release of the analyte strongly depended on the analytes, and the substance specific delayed release allowed for baseline-separated discrimination of the analytes.
ANALYTICAL CHEMISTRY
(2022)
Article
Engineering, Chemical
Xinpei Wang, Chao Qian, Shi-Ya Tang, Shaodong Zhou
Summary: This study couples ammonia synthesis with methane conversion under plasma conditions using Fe-Al composite metal oxides as catalyst, resulting in shortened process for ammonia production and high selectivity in generating C-2 hydrocarbon byproducts. To overcome the activation barrier for methane and nitrogen, dielectric barrier discharge technology is employed to input high-quality energy into the reaction system. Examination of various 3d-metal oxides, SiO2, and Al2O3 leads to the identification of Fe-Al composite metal oxide as the catalyst of choice. The catalyst's structure is characterized using XRD, XPS, TGA, and BET techniques.
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
(2023)
Article
Biochemical Research Methods
Christopher Kuhlmann, Jacob T. Shelley, Carsten Engelhard
JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY
(2019)
Article
Biochemical Research Methods
Maria E. Rivera-Albarran, Steven J. Ray
JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY
(2020)
Review
Spectroscopy
Christopher J. Brais, Jaime Orejas Ibanez, Andrew J. Schwartz, Steven J. Ray
Summary: Time-of-flight mass spectrometry (TOFMS) is a powerful and simple approach in mass spectrometry, requiring continuous innovation and development. New instrumental technologies enable the application of TOFMS in chemical measurement, such as ion acceleration, multiplexed detection, and extension of ion flight time.
MASS SPECTROMETRY REVIEWS
(2021)
Review
Spectroscopy
Brian T. Molnar, Jacob T. Shelley
Summary: Plasmas have been used as ionization sources in mass spectrometry experiments since the early days of Thomson and Aston. Plasma ion sources were chosen because they were one of the few known sources of gas-phase ions at the time and were relatively easy to set up and operate. The development of plasma ionization has led to advancements in mass spectrometry and laid the foundation for ionization approaches, mass analysis, and detection methods for very large molecules.
MASS SPECTROMETRY REVIEWS
(2021)
Article
Biochemistry & Molecular Biology
Shankar Pandey, Yuanyuan Li, Montwaun D. Young, Shankar Mandal, Laichun Lu, Jacob T. Shelley, Hanbin Mao
Article
Spectroscopy
Nicholas Hazel, Jaime Orejas, Steven J. Ray
Summary: The Solution Cathode Glow Discharge (SCGD) is a promising novel atmospheric-pressure glow discharge plasma for atomic emission spectrometry. Direct analysis of metallic nanoparticles revealed size-dependent sensitivity differences when compared to free-ion standard solutions, requiring acid digestion for accurate quantitation. Experimental parameters and surfactant additions were found to affect atomic emission, with potential implications for material transfer mechanisms into the plasma.
SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY
(2021)
Article
Spectroscopy
Sunil P. Badal, Paul B. Farnsworth, George C-Y Chan, Brian T. Molnar, Jessica R. Hellinger, Jacob T. Shelley
Summary: Plasma-based ambient desorption/ionization sources often use helium as the primary discharge gas, but studies show advantages of mixed-gas plasmas. Adding H-2 to helium can decrease reagent-ion signals while preserving analyte-ion signals. Nitrogen addition increases negative reagent ions for enhanced ion signal of specific compounds. Various molecular gases impact emission characteristics and plasma parameters in mixed-gas systems.
SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY
(2021)
Article
Chemistry, Analytical
Yi You, Linxia Song, Montwaun D. Young, Matthew van der Wielen, Theresa Evans-Nguyen, Jens Riedel, Jacob T. Shelley
Summary: This method reconstructs single-component mass spectra by exploiting chemical information encoded in the time domain, improving interpretability and searchability. It uses a modified cross-correlation algorithm to compute a metric describing the similarity of features within ion chronograms. An automatic workflow can quickly categorize mass spectral peaks.
ANALYTICAL CHEMISTRY
(2021)
Article
Physics, Applied
Nicholas Hazel, Jaime Orejas, Steven Ray
Summary: The effects of an external magnetic field on SCGD and SAGD were investigated, with a rotating external magnetic field found to change discharge structure and spatial emission pattern, ultimately improving detection limits.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Physics, Applied
Courtney L. Walton, Andrew J. Schwartz, Jacob T. Shelley
Summary: Solution-electrode glow discharges have shown great utility as ionization sources for mass spectrometry, with solution composition influencing analyte-ion formation. The addition of methanol to an atmospheric-pressure solution-cathode glow discharge increased molecular- and fragment-ion signals for angiotensin II peptide, likely due to improved desolvation and enhanced interaction of analyte molecules with glow-discharge species. High-boiling-point reagents inhibited fragmentation but lowered intact molecular-ion signals, with loss of fragment ions correlating with the boiling point of the reagent used. These findings suggest that changing the composition of the SCGD solution can alter analytical performance and provide insight into analyte ionization and fragmentation processes.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Spectroscopy
Jaime Orejas, Nicholas Hazel, Steven J. Ray
Summary: The solution-cathode glow discharge (SCGD) using a novel rectangular-shaped cathode capillary is employed to study aspects of the plasma-liquid interface, with high-speed video and low-angle laser scattering techniques used to evaluate potential mechanisms related to surface-plasma interaction. Frame-by-frame analysis of high-speed video allows estimation of droplet number density, translational speed, and rate of ejection, providing insight into potential analyte transport mechanisms important for analytical atomic spectrometry using SCGD.
SPECTROCHIMICA ACTA PART B-ATOMIC SPECTROSCOPY
(2021)
Article
Physics, Atomic, Molecular & Chemical
Christopher J. Brais, Steven J. Ray
Summary: A novel computational method is developed to calculate the mass bias of orthogonal acceleration time-of-flight mass spectrometers by considering the energy-dependent transmission of ions and the ion sampling efficiency. The method estimates the resultant mass bias by evaluating these factors and can be applied to different ionization sources and ion energy distributions.
INTERNATIONAL JOURNAL OF MASS SPECTROMETRY
(2022)
Article
Physics, Atomic, Molecular & Chemical
Ifeoluwa Ayodeji, Alexandra Keidel, Nelson Perdomo, Jacob Shelley, Theresa Evans-Nguyen
Summary: The characterization of uranium and other radionuclides is important to nuclear forensics. Isotope-ratio mass spectrometry (IRMS) is commonly used in the laboratory, but is not practical for real-time measurements. Ion mobility instruments, particularly differential mobility spectrometry (DMS), coupled with ion trap mass spectrometry (MS), show promise for on-site IR analysis. DMS can remove chemical interferences and improve the accuracy of the MS. The results of the study demonstrate that DMS can enhance the confidence of nuclear IRMS measurements.
INTERNATIONAL JOURNAL OF MASS SPECTROMETRY
(2022)
Article
Chemistry, Analytical
Nicholas Hazel, Jaime Orejas Ibanez, Steven Ray
Summary: This paper reports a novel Solution-Cathode Glow-Discharge (SCGD) system, which creates a sheet-like plasma to improve optical sampling efficiency by changing the structure of the anode and the cathode. Compared with conventional SCGD, the horizontal cathode SCGD shows higher sensitivity and lower detection limits for the analysis of 24 elements.
JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY
(2022)
Meeting Abstract
Chemistry, Multidisciplinary
Ifeoluwa Ayodeji, Theresa Evans-Nguyen, Sunil Badal, Garett MacLean, Jacob Shelley
ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY
(2019)