Engineering topics

Danielson, William F

Publications and source records attributed to Danielson, William F.

5 records

DOE OSTI2013

High-Definition Differential Ion Mobility Spectrometry with Resolving Power up to 500

As the resolution of analytical methods improve, further progress tends to be increasingly limited by instrumental parameter instabilities that could be ignored before. This is now the case with differential ion mobility spectrometry (FAIMS), where fluctuations of the voltages and gas pressure have become critical. A new high-definition generator for FAIMS compensation voltage reported here provides a stable and accurate output than can be scanned with negligible steps. This reduces the spectral drift and peak width, thus improving the resolving power (R) and resolution. The gain for multiply-charged peptides that have narrowest peaks is up to ~40%, and R ~ 400 - 500 is achievable using He/N2 or H2/N2 gas mixtures.

Environmental Molecular Sciences Laboratory↗

DOE OSTI2012

Advanced Mass Spectrometry for Proteomics and Other Biological Applications

The purpose of the collaboration between Agilent Technologies and Battelle is to integrate Battelle’s unique electrospray ionization ion mobility spectrometry (ESI/IMS) technology with Agilent’s state-of-art time of flight mass spectrometry (TOF MS) to design and fabricate multiple ESI/IMS/TOF MS instrument platforms for large scale demonstration of proteomics analyses. The development is aimed at the firm foundation for a premium new IMS/MS product for Agilent and the dissemination of important analytical advances for the scientific community Three initial prototype systems are planned to be utilized as part of this effort. These are as follows: - Prototype 1: This prototype will based upon the integration of Battelle’s existing IMS Version 3 front-end with the latest version of Agilent’s TOF instrument (the SEIKO TOF) that will include an upgraded high-speed ADC. - Prototype 2: This prototype will be based on the integration of Battelle’s more advanced IMS Version 4 front-end with an existing Agilent TOF system already installed at PNNL. - Prototype 3: This prototype will be based on the integration of a modified IMS Version 4 front-end with Agilent’s most advanced TOF instruments. The collaboration consists of four tasks based on the prototypes and these are: - Task 1. Assembly and Testing of Prototype 1 - Task 2. Assembly and Testing of Prototype 2 - Task 3. Fabrication, Assembly, and Testing of Prototype 3 - Task 4. Final report

Baker, Erin Shammel↗

DOE OSTI2011

Hydrodynamic injection with pneumatic valving for microchip electrophoresis with total analyte utilization

A novel hydrodynamic injector that is directly controlled by a pneumatic valve has been developed for reproducible microchip capillary electrophoresis (CE) separations. The poly(dimethylsiloxane) (PDMS) devices used for evaluation comprise a separation channel, a side channel for sample introduction, and a pneumatic valve aligned at the intersection of the channels. A low pressure (≤ 3 psi) applied to the sample reservoir is sufficient to drive sample into the separation channel. The rapidly actuated pneumatic valve enables injection of discrete sample plugs as small as ~100 pL for CE separation. The injection volume can be easily controlled by adjusting the intersection geometry, the solution back pressure and the valve actuation time. Sample injection could be reliably operated at different frequencies (< 0.1 Hz to >2 Hz) with good reproducibility (peak height relative standard deviation ≤ 3.6%) and no sampling biases associated with the conventional electrokinetic injections. The separation channel was dynamically coated with a cationic polymer, and FITC-labeled amino acids were employed to evaluate the CE separation. Highly efficient (≥ 7.0 × 103 theoretical plates for the ~2.4 cm long channel) and reproducible CE separations were obtained. The demonstrated method has numerous advantages compared with the conventional techniques, including repeatable and unbiased injections, no sample waste, high duty cycle, controllable injected sample volume, and fewer electrodes with no need for voltage switching. The prospects of implementing this injection method for coupling multidimensional separations, for multiplexing CE separations and for sample-limited bioanalyses are discussed.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2011

Pulsed Multiple Reaction Monitoring Approach to Enhancing Sensitivity of a Tandem Quadrupole Mass Spectrometer

Liquid chromatography (LC)-triple quadrupole mass spectrometers operating in a Multiple Reaction Monitoring (MRM) mode are increasingly used for quantitative analysis of low abundance analytes in highly complex biochemical matrices. After development and selection of optimum MRM transition, sensitivity and data quality limitations are largely related to mass spectral peak interferences from sample or matrix constituents and statistical limitations at low number of ions reaching the detector. Herein, we report a new approach to enhancing MRM sensitivity by converting the continuous stream of ions from the ion source into a pulsed ion beam through the use of an Ion Funnel Trap (IFT). Evaluation of the pulsed MRM approach was performed with a tryptic digest of Shewanella oneidensis strain MR-1 spiked with several reference peptides. The sensitivity improvement observed with the IFT coupled to the triple quadrupole instrument is based on several unique features. First, ion accumulation in the radio frequency (RF) ion trap facilitates improved droplet desolvation, which is manifested in the reduced background ion noise at the detector. Second, signal amplitude for a given transition is enhanced because of an order-of-magnitude increase in the ion charge density per unit time compared to a continuous mode of operation. Third, signal detection at the full duty cycle is obtained, as the trap use eliminates dead times between transitions, which are inevitable with continuous ion streams. In comparison with the conventional approach, the pulsed MRM signals showed up to 5-fold enhanced peak amplitude and 2-3 fold reduced chemical background, resulting in an improvement in the limit of detection (LOD) by a factor of ~ 4 to ~ 8.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2010

An efficient data format for mass spectrometry based proteomics

The diverse range of mass spectrometry (MS) instrumentation along with corresponding proprietary and non-proprietary data formats has generated a proteomics community driven call for a standardized format to facilitate management, processing, storing, visualization, and exchange of both experimental and processed data. To date, significant efforts have been extended towards standardizing XML-based formats for mass spectrometry data representation, despite the recognized inefficiencies associated with storing large numeric datasets in XML. The proteomics community has periodically entertained alternate strategies for data exchange, e.g., using a common application programming interface or a database-derived format. However these efforts have yet to garner significant attention, mostly because they haven’t illustrated significant performance benefits over existing standards, but also due to issues such as extensibility to multi-dimensional separation systems, robustness of operation, and incomplete or mismatched vocabulary. Here, we describe a format based on standard database principles that offers multiple benefits over existing formats in terms of storage size, ease of processing, data retrieval times and extensibility to accommodate multi-dimensional separation systems.

99 GENERAL AND MISCELLANEOUS↗