August Specht - Academia.edu (original) (raw)

Papers by August Specht

Research paper thumbnail of Simplex Optimization Methods for Instrumentation Tuning

Research paper thumbnail of Linear Ion Processing Apparatus With Improved Mechanical Isolation and Assembly

Research paper thumbnail of Laser desorption: Laser photoionization ion trap mass spectrometry for the direct analysis of solid samples

This thesis describes work associated with the creation of a novel analytical instrument, a two-l... more This thesis describes work associated with the creation of a novel analytical instrument, a two-laser ion trap mass spectrometer. This device combines one of the most sensitive and selective direct solid sampling techniques, two-laser solid sampling, with a very versatile mass spectrometer, the ion trap. This work demonstrates some of the potential advantages associated with coupling these two techniques. The

Research paper thumbnail of Direct Determination of Polycyclic Aromatic Hydrocarbons in Solid Matrices Using Laser Desorption/Laser Photoionization Ion Trap Mass Spectrometry

Journal of the American Society For Mass Spectrometry, Jun 30, 2003

The development and characterization of a new instrument for solid sampling which couples IR lase... more The development and characterization of a new instrument for solid sampling which couples IR laser desorption followed by UV laser photo-ionization and analysis using an ion trap mass spectrometer has been investigated. For calibration, a new type of solid sample preparation involving activated charcoal as the solid substrate was used. This solid sample provided a steady signal for several thousand laser shots, which allowed optimization of the experimental procedure. It was found that both the IR and UV intensity and the delay between them play an important role in both the magnitude and type of signals observed. A method of gas phase accumulation with multiple laser shots was examined. Finally, this technique was demonstrated to be effective in providing direct qualitative information for N.I.S.T. SRM 1944 river sediment sample with no sample pre-treatment.

Research paper thumbnail of Quantitation of TMT-Labeled Peptides Using Higher-Energy Collisional Dissociation on the Velos Pro Ion Trap Mass Spectrometer

Research paper thumbnail of The use of UV-MS correlation for the quantification of plasma metabolites on a dual-cell linear ion trap

The quantitative assessment of metabolites in samples from development in vivo studies has become... more The quantitative assessment of metabolites in samples from development in vivo studies has become an area of increasing study with the release of guidances from regulatory bodies (MIST and M3 R2) and their subsequent interpretation and implementation. The hurdles faced in metabolite identification are joined by obtaining quantitative levels on relevant metabolites for which absolute structure may not be known and for which reference standards are not available. The challenges of matrix suppression, analyte stability, and MS detector response factor make quantitation of metabolites based on a parent drug standard almost impossible. We have applied a UV correlation to assign concentrations to metabolites identified from in vitro generated samples and used the results to quantify plasma samples on the same instrument. Initially, metabolites of dextromethorphan were generated in vitro through incubations with human liver S9 fraction (2 mg/mL). Dextromethorphan was incubated for 2 hours ...

Research paper thumbnail of Direct determination of polycyclic aromatic hydrocarbons in solid matrices using laser desorption/laser photoionization ion trap mass spectrometry

Journal of the American Society for Mass Spectrometry, 2003

The development and characterization of a new instrument for solid sampling which couples IR lase... more The development and characterization of a new instrument for solid sampling which couples IR laser desorption followed by UV laser photo-ionization and analysis using an ion trap mass spectrometer has been investigated. For calibration, a new type of solid sample preparation involving activated charcoal as the solid substrate was used. This solid sample provided a steady signal for several thousand laser shots, which allowed optimization of the experimental procedure. It was found that both the IR and UV intensity and the delay between them play an important role in both the magnitude and type of signals observed. A method of gas phase accumulation with multiple laser shots was examined. Finally, this technique was demonstrated to be effective in providing direct qualitative information for N.I.S.T. SRM 1944 river sediment sample with no sample pre-treatment.

Research paper thumbnail of Automated On-Line Isotope Dilution Analysis with ICP-MS Using Sandwich Flow Injection

Analytical Chemistry, 1998

An automated flow injection (FI) manifold is described to perform the addition of isotopic spikes... more An automated flow injection (FI) manifold is described to perform the addition of isotopic spikes to aqueous samples on-line with ICP-MS for isotope dilution (ID) analysis. The manifold uses the sandwich technique (with the nested loop approach) to perform an injection of the isotopic spike solution within a sample (or standard) plug, the resulting sample-spike-sample sequence being pushed toward the nebulizer by a 1% HNO 3 carrier. A standard, which must contain one element not present in the spike solution to allow the determination of the dispersion coefficient, must also be used to allow a reverse isotope dilution analysis, as well as corrections for mass discrimination and/or spectroscopic interferences. Indeed, because the signals from the individual isotopes are monitored continuously, only one isotope free of spectroscopic interference is required for elements whose isotopic distribution does not vary in nature (two isotopes are still needed for the other elements), as a correction for the interference can be made by comparison with the signals from the standard. Furthermore, this automated approach makes ID-ICP-MS a faster method and does not require any preliminary analysis of the sample because the concentration profile resulting from FI allows the selection of the best isotopic ratio. It was successfully applied to the determination of Mo in saline water.

Research paper thumbnail of On-Line Isotope Dilution Analysis with ICPMS Using Reverse Flow Injection

Analytical Chemistry, 1997

A simple flow injection manifold is described to perform the addition of isotopic spikes to aqueo... more A simple flow injection manifold is described to perform the addition of isotopic spikes to aqueous samples online with ICPMS. The analysis involves one multielement spike injection in the sample carrier and another injection of the spike solution in a standard carrier. This standard must contain one element which is not present in the spike solution, to allow the determination of the dispersion coefficient. The same standard also allows a reverse isotope dilution (ID) analysis, in addition to corrections for mass discrimination and any spectroscopic interference on one of the two isotopes used for the ID analysis. This flow injection approach, therefore, requires only one isotope free of spectroscopic interference for elements whose isotopic distribution does not vary in nature (two isotopes are still needed for other elements since the "natural" ratio must then also be determined). No preliminary analysis of the sample is required prior to the actual ID analysis. Furthermore, the concentration profile resulting from the flow injection allows the selection of the best isotopic ratio in terms of error propagation. This approach, therefore, makes ID analysis as simple as an external calibration but with added accuracy and precision. It was successfully applied to the analysis of a river water certified reference material and to saline water.

Research paper thumbnail of Novel Parallelized Quadrupole/Linear Ion Trap/Orbitrap Tribrid Mass Spectrometer Improving Proteome Coverage and Peptide Identification Rates

Analytical Chemistry, 2013

Proteome coverage and peptide identification rates have historically advanced in line with improv... more Proteome coverage and peptide identification rates have historically advanced in line with improvements to the detection limits and acquisition rate of the mass spectrometer. For a linear ion trap/Orbitrap hybrid, the acquisition rate has been limited primarily by the duration of the ion accumulation and analysis steps. It is shown here that the spectral acquisition rate can be significantly improved through extensive parallelization of the acquisition process using a novel mass spectrometer incorporating quadrupole, Orbitrap, and linear trap analyzers. Further, these improvements to the acquisition rate continue to enhance proteome coverage and general experimental throughput.

Research paper thumbnail of Resonance enhanced multiphoton dissociation of polycyclic aromatic hydrocarbons cations in an RF ion trap

Chemical Physics Letters, 2003

We present a novel method for recording the absorption spectra of cations of non-volatile molecul... more We present a novel method for recording the absorption spectra of cations of non-volatile molecules using resonance enhanced multiphoton dissociation of trapped ions. Ions are produced through a 2-laser desorption/ionization process in an RF ion trap mass-spectrometer. A third tunable visible laser induces fragmentation of the trapped ions with a yield dependent on the absorption cross-sections of the ions. Using this method we have recorded the visible absorption spectrum of two PAH isomers, phenanthrene and anthracene.

Research paper thumbnail of Simplex Optimization Methods for Instrumentation Tuning

Research paper thumbnail of Linear Ion Processing Apparatus With Improved Mechanical Isolation and Assembly

Research paper thumbnail of Laser desorption: Laser photoionization ion trap mass spectrometry for the direct analysis of solid samples

This thesis describes work associated with the creation of a novel analytical instrument, a two-l... more This thesis describes work associated with the creation of a novel analytical instrument, a two-laser ion trap mass spectrometer. This device combines one of the most sensitive and selective direct solid sampling techniques, two-laser solid sampling, with a very versatile mass spectrometer, the ion trap. This work demonstrates some of the potential advantages associated with coupling these two techniques. The

Research paper thumbnail of Direct Determination of Polycyclic Aromatic Hydrocarbons in Solid Matrices Using Laser Desorption/Laser Photoionization Ion Trap Mass Spectrometry

Journal of the American Society For Mass Spectrometry, Jun 30, 2003

The development and characterization of a new instrument for solid sampling which couples IR lase... more The development and characterization of a new instrument for solid sampling which couples IR laser desorption followed by UV laser photo-ionization and analysis using an ion trap mass spectrometer has been investigated. For calibration, a new type of solid sample preparation involving activated charcoal as the solid substrate was used. This solid sample provided a steady signal for several thousand laser shots, which allowed optimization of the experimental procedure. It was found that both the IR and UV intensity and the delay between them play an important role in both the magnitude and type of signals observed. A method of gas phase accumulation with multiple laser shots was examined. Finally, this technique was demonstrated to be effective in providing direct qualitative information for N.I.S.T. SRM 1944 river sediment sample with no sample pre-treatment.

Research paper thumbnail of Quantitation of TMT-Labeled Peptides Using Higher-Energy Collisional Dissociation on the Velos Pro Ion Trap Mass Spectrometer

Research paper thumbnail of The use of UV-MS correlation for the quantification of plasma metabolites on a dual-cell linear ion trap

The quantitative assessment of metabolites in samples from development in vivo studies has become... more The quantitative assessment of metabolites in samples from development in vivo studies has become an area of increasing study with the release of guidances from regulatory bodies (MIST and M3 R2) and their subsequent interpretation and implementation. The hurdles faced in metabolite identification are joined by obtaining quantitative levels on relevant metabolites for which absolute structure may not be known and for which reference standards are not available. The challenges of matrix suppression, analyte stability, and MS detector response factor make quantitation of metabolites based on a parent drug standard almost impossible. We have applied a UV correlation to assign concentrations to metabolites identified from in vitro generated samples and used the results to quantify plasma samples on the same instrument. Initially, metabolites of dextromethorphan were generated in vitro through incubations with human liver S9 fraction (2 mg/mL). Dextromethorphan was incubated for 2 hours ...

Research paper thumbnail of Direct determination of polycyclic aromatic hydrocarbons in solid matrices using laser desorption/laser photoionization ion trap mass spectrometry

Journal of the American Society for Mass Spectrometry, 2003

The development and characterization of a new instrument for solid sampling which couples IR lase... more The development and characterization of a new instrument for solid sampling which couples IR laser desorption followed by UV laser photo-ionization and analysis using an ion trap mass spectrometer has been investigated. For calibration, a new type of solid sample preparation involving activated charcoal as the solid substrate was used. This solid sample provided a steady signal for several thousand laser shots, which allowed optimization of the experimental procedure. It was found that both the IR and UV intensity and the delay between them play an important role in both the magnitude and type of signals observed. A method of gas phase accumulation with multiple laser shots was examined. Finally, this technique was demonstrated to be effective in providing direct qualitative information for N.I.S.T. SRM 1944 river sediment sample with no sample pre-treatment.

Research paper thumbnail of Automated On-Line Isotope Dilution Analysis with ICP-MS Using Sandwich Flow Injection

Analytical Chemistry, 1998

An automated flow injection (FI) manifold is described to perform the addition of isotopic spikes... more An automated flow injection (FI) manifold is described to perform the addition of isotopic spikes to aqueous samples on-line with ICP-MS for isotope dilution (ID) analysis. The manifold uses the sandwich technique (with the nested loop approach) to perform an injection of the isotopic spike solution within a sample (or standard) plug, the resulting sample-spike-sample sequence being pushed toward the nebulizer by a 1% HNO 3 carrier. A standard, which must contain one element not present in the spike solution to allow the determination of the dispersion coefficient, must also be used to allow a reverse isotope dilution analysis, as well as corrections for mass discrimination and/or spectroscopic interferences. Indeed, because the signals from the individual isotopes are monitored continuously, only one isotope free of spectroscopic interference is required for elements whose isotopic distribution does not vary in nature (two isotopes are still needed for the other elements), as a correction for the interference can be made by comparison with the signals from the standard. Furthermore, this automated approach makes ID-ICP-MS a faster method and does not require any preliminary analysis of the sample because the concentration profile resulting from FI allows the selection of the best isotopic ratio. It was successfully applied to the determination of Mo in saline water.

Research paper thumbnail of On-Line Isotope Dilution Analysis with ICPMS Using Reverse Flow Injection

Analytical Chemistry, 1997

A simple flow injection manifold is described to perform the addition of isotopic spikes to aqueo... more A simple flow injection manifold is described to perform the addition of isotopic spikes to aqueous samples online with ICPMS. The analysis involves one multielement spike injection in the sample carrier and another injection of the spike solution in a standard carrier. This standard must contain one element which is not present in the spike solution, to allow the determination of the dispersion coefficient. The same standard also allows a reverse isotope dilution (ID) analysis, in addition to corrections for mass discrimination and any spectroscopic interference on one of the two isotopes used for the ID analysis. This flow injection approach, therefore, requires only one isotope free of spectroscopic interference for elements whose isotopic distribution does not vary in nature (two isotopes are still needed for other elements since the "natural" ratio must then also be determined). No preliminary analysis of the sample is required prior to the actual ID analysis. Furthermore, the concentration profile resulting from the flow injection allows the selection of the best isotopic ratio in terms of error propagation. This approach, therefore, makes ID analysis as simple as an external calibration but with added accuracy and precision. It was successfully applied to the analysis of a river water certified reference material and to saline water.

Research paper thumbnail of Novel Parallelized Quadrupole/Linear Ion Trap/Orbitrap Tribrid Mass Spectrometer Improving Proteome Coverage and Peptide Identification Rates

Analytical Chemistry, 2013

Proteome coverage and peptide identification rates have historically advanced in line with improv... more Proteome coverage and peptide identification rates have historically advanced in line with improvements to the detection limits and acquisition rate of the mass spectrometer. For a linear ion trap/Orbitrap hybrid, the acquisition rate has been limited primarily by the duration of the ion accumulation and analysis steps. It is shown here that the spectral acquisition rate can be significantly improved through extensive parallelization of the acquisition process using a novel mass spectrometer incorporating quadrupole, Orbitrap, and linear trap analyzers. Further, these improvements to the acquisition rate continue to enhance proteome coverage and general experimental throughput.

Research paper thumbnail of Resonance enhanced multiphoton dissociation of polycyclic aromatic hydrocarbons cations in an RF ion trap

Chemical Physics Letters, 2003

We present a novel method for recording the absorption spectra of cations of non-volatile molecul... more We present a novel method for recording the absorption spectra of cations of non-volatile molecules using resonance enhanced multiphoton dissociation of trapped ions. Ions are produced through a 2-laser desorption/ionization process in an RF ion trap mass-spectrometer. A third tunable visible laser induces fragmentation of the trapped ions with a yield dependent on the absorption cross-sections of the ions. Using this method we have recorded the visible absorption spectrum of two PAH isomers, phenanthrene and anthracene.