The Multi User Mass Spectrometry Laboratory of the Division of Chemistry and Chemical Engineering provides analytical services on a variety of mass spec platforms.
Open Access is granted to registered users for many of these instruments. The lab manager provides additional support and guidance for more complex methodologies, instrumentation and data analysis.
JEOL JMS-T2000GC "AccuTOF™ GC-Alpha"
The JMS-T2000GC AccuTOF™ GC-Alpha is a high-performance GC-MS system that simultaneously realizes high mass resolution, high mass accuracy, high sensitivity, high speed data acquisition, wide dynamic range, and wide mass range. Performance Specifications of the JMS-T2000GC AccuTOF™
- High Speed Data Acquisition: 50 Hz
- Wide Mass Range: ~m/z 6,000
- High Mass Resolving Power: 30,000
- High Mass Accuracy: 1 ppm*1
The Caltech AccuTOF™ GC-Alpha will be equipped with multiple ionization capabilities:
EI (Electron Ionization), which is the most widely used ionization technique in GC-MS.
EI is superior in sensitivity and reproducibility, and is supported by a variety of library searchable databases. However, EI generates numerous fragment ions and often fails to show strong molecular ion signals. Consequently, qualitative analysis results may be incorrect if they solely rely on database searches.
Thus, it is critical in GC-MS analysis to enhance the accuracy of qualitative analysis by using various soft ionization techniques in addition to EI.
CI (Chemical ionization) uses a reagent gas to ionize sample molecules through ion–molecule reactions in the gas phase. The degree of fragmentation observed in CI depends on the difference in the proton affinities of the analyte and the reagent gas.
FI and FD (Field Ionization and Field Desorption) are ideal soft ionization techniques for molecular weight determination because they provide lower internal energy to the analytes than EI and even CI, thus producing clear molecular ions.
In FI the sample introduced through GC. In FD the sample is carefully applied onto an emitter, and directly introduced into the ion source.
FD is useful for
- analysis of thermally labile compounds.
- samples soluble in nonpolar solvents.
- powder samples dispersible in solvents.
- low- to mid-polar metal complexes.
- High molecular weight samples not supported in GC-MS.
LIFDI (liquid injection field desorption/ionization) for mass analysis of air-sensitive samples LIFDI (https://www.linden-cms.de) is a technique to admit sample, either as solution or sample vapor, to the emitter via a fused silica capillary while the emitter is in vacuum and positioned inside the ion source.
To learn more about JMS-T200GC please visit https://www.jeol.co.jp/en/products/detail/JMS-T2000GC.html
(acquired in 2010 with funds from an HHMI Undergraduate Grant)
Access: Open Ionization: ESIAnalyzer: linear ion trapm/z range: generally 150-2000MS/MS capability: YesSoftware: XCalibur The LTQ is equipped with an electrospray ionization source. It may be operated in direct infusion mode or interfaced with a liquid-chromatography (LC) system.
(acquired in 2005 with funds from an NSF CRIF Grant)
The LCT Premier XE is a time-of-flight mass spectrometer equipped with an electrospray ionization source. Instrument operation alternates between direct infusion mode and on-line LC-MS depending on lab and research needs. Access: Open/Assisted Ionization: ESIAnalyzer: TOFm/z range: generally 150-2000Resolution: 5,000 in V mode and 10,000 in W modeAccurate Mass Capability: yes (staff only)Mode: direct infusion and UPLC-MS
(acquired in 2016 with funds from DOW Foundation Grant)
The Autoflex is a state-of-the art matrix-assisted laser desorption ionization (MALDI) instrument used for analysis of mostly large synthetic and biopolymers. Ionization: MALDIAnalyzer: TOFm/z range: generally 500 Da-120 kDaSoftware: FlexControl and FlexAnalysis
Instrument Use Policy
With the exception of the magnetic sector instrument (JMS-600H), which is operated by lab personnel ONLY, the remaining mass spectrometers are available for individual use after training.
All users must complete User Registration Form prior to training on the instrument(s) they plan to use. A one-time training fee of $75 will be charged to your PTA.
Trained users may book instrument time by signing the calendar for each mass spectrometer using the following web link: http://chemex.che.caltech.edu/cal/webcal-3/webcal.cgi. If you need to use the instrument for more than two hours at one time you will need to consult the lab manager.
Mass Spec User List
Users of the lab are advised to subscribe to the mass spec user list to be alerted of instrument status and lab closures and changes to policies. https://lists.caltech.edu/listinfo/massspec_lab
Users must observe safe lab procedures. Please notify lab personnel if there is any condition that prevents use of the instrument or endangers the safety of those present in the lab.
Users must sign into the logbook before beginning to work on the instrument and complete the time-of-use form after completion of their work.
All users must verify cleanliness of the instrument before and after running their own samples. Work area must be left clear of debris including, used gloves, KimWipes, etc.
Lab entry is via keypad code. This code will be shared at the discretion of the lab manager.
Users who intentionally or neglectfully misuse, damage, or contaminate the instruments and/or solvents will lose their privilege to use the instruments, and will be billed for any repairs, cleanup or decontamination. This includes but is not limited to physical damage, chemical contamination, or corruption of the data systems.
Users are not to use the instrument control computers for SURFING on the web, playing games, downloading music, or emailing data.
Policy Regarding Preservation of Data
Lab personnel transfer data from instrument control computers to a local server (Seabiscuit) at intervals; the Seabiscuit server is also mirrored onto a second disk. Still, disk capacity is limited and ultimately even the data on the server have to be archived. Users are thus asked to bring a flash drive with them to back up their data. Each computer is connected to a router with multiple USB ports. Please use these ports instead of the USB port on the computer.
Guidelines for Acknowledgement in Print
The CCE Multiuser Mass Spectrometry lab in Crellin B170 is a shared mass spectrometry laboratory. The mass spectrometers in this lab have been using funds from NSF (CRIF and MRSEC programs), Hughes Foundation, DOW, and CCE Division funds. Please acknowledge the lab in your publications to assist in acquisition of future funds needed to update its equipment. Acknowledgement may be in this form:
"This research was enabled/benefited from the use of instrumentation made available by the Caltech CCE Multiuser Mass Spectrometry Laboratory." Please email an electronic copy of any publication that made use of this lab's services.
Please note that instrument time is charged on the basis of actual time used with a minimum visit time of 15 minutes and increments specific to each instrument. If you would like to use the facility and are external to Caltech, please contact Mona Shahgoli at (626) 395-3372.
Facilities Use/Technical Services Agreement Form
Mona Shahgholi, Ph.D.
Telephone: (626) 395-3372
email: [email protected]
1200 East California Blvd
Pasadena, CA 91125