| |
Mass Spectrometry Facility is located in Room 402 of the Physical Sciences Building. It is equipped with two GC/ MS Instruments and a MALDI-TOF MS and is operated by Jedrzej Romanowicz.
| |
Hewlett-Packard 5987A general use; research and training (at present out of order) |
Shimadzu QP5050A general use; research and training |
GC |
|
|
| |
Capillary Column 0.25mm/30m/0.25um
5%-phenyl, 95%-methylpolysiloxane |
Capillary Column 0.25mm/30m/0.25um
5%-phenyl, 95%-methylpolysiloxane |
Injection |
split, ca. 50:1; not user adjustable |
split user adjustable, usually 50:1 |
Splitless injection |
Yes |
Yes |
Carrier gas |
Helium, ca. 1.2 ml/min |
Helium, 1.2 ml/min |
Typical temperature profile |
Injector 200C
Oven initial temp. 50C
Initial time 2min
Ramp rate 10C/min
Final temp. 250C
Final time 10min |
Injector 200C
Initial time 2min
Ramp rate 10C/min
Final temp. 250C
Final time 10min |
Interface |
capillary direct; temp 275C
|
capillary direct; temp 270C |
MS |
|
|
pumping
vacuum |
separate diffusion pumps for ion source and detector chamber
<4.0 x10-6 Torr |
one turbomolecular pump
2x10-3Pa (1.5x10-5Torr) |
ion source |
same for EI and CI |
separate for EI and CI
CI gas: Methane |
Mass analyzer |
quadrupole |
quadrupole |
Scan range |
full 10-1000m/z;
typical 35-450 |
full 10-920 m/z;
typical 45-550 |
Direct Insertion Probe |
No |
Yes |
Any student, postdoc or faculty member is welcome to take part in a practical GC/MS course, which gives basic information on how these instruments work and teaches how to operate them. Successful completion of this training allows people to operate GC/MS by themselves at any time. Otherwise, samples need to be submitted to the Facility
The requirements for the samples:
- Must be in a closed, clearly marked vial (no open containers of any kind are acceped)
- Dissolve in a low boiling point solvent (avoid water)
- Concentration:
- for GC/MS ca. 0.5 mM
- for DIP ca. 0.1 mM
- Volatile; for GC/MS b.p. < 350C
- Thermally stable
- Free from inorganic salts and acids
We can also analyze samples submitted by outside parties for a fee.
The newest newest spectrometer in our Facility is MALTI-TOF Bruker Daltonics Omiflex. It is a linear mass spectrometer (being equipped with delayed extraction and reflectron) designed for mass analysis of compounds (macromolecules up to several hundred thousand Daltons) using the technique known as Matrix Assisted Laser Desorption Ionization or MALDI.
In MALDI a sample of interest is dissolved into a highly concentrated solution of matrix material. A droplet of this solution is allowed to air dry on a steel substrate specially designed for use with the Omniflex. When dried, the sample consists of crystals of matrix embedded with the analyte molecules. After the target is inserted into the instrument, a pulsed laser beam is directed onto the sample to form ions. Once in the gas phase, collisions between the analyte molecules and excited matrix molecules effect ionization of some portion of the analyte molecules. The newly formed analyte ions are then accelerated into a Time-Of-Flight (TOF) mass analyzer. Because the ions are given the same energy, ions of different masses travel to the detector at different velocities. By the time the ions strike the detector, the initial cluster of ions formed by laser has separated according to their mass-to-charge ratio, m/z. The Omniflex collects the detector signals and sums them together to produce a mass spectrum of the sample.
Like the other mass spectrometers, the Omniflex can be operated only by authorized users. To become an authorized user, please contact me for training.
Jedrzej Romanowicz
jromano@bgsu.edu
Phone: (419) 372-7514
|
|
