| The open access instruments
are located in 38 Lewis Hall and are available for graduate student
use. Only members of the facility have access to the open access instruments.
The laboratory is open 24 hours a day, seven days a week. Authorized
users may sign up for time using the calendars provided in 38 Lewis
Hall. From 9 a.m. to 5 p.m. Monday through Friday a 3-hour time limit
applies. There is no limit during off hours. Overnight runs must be
completed by 9 a.m.
GC/MS: Students
are required to make an appointment for a short (1 hour or so) training
period during which they are checked-out on the instrument. We encourage
students to bring a sample of their own to the training session
to practice setting up gradient profiles. Please see Dr. Zhongrui
Zhou about GC/MS training.
LC/MS: The LC/MS
instrument consists of a quadrupole mass spectrometer and a liquid
chromatography system. The mass spectrometer has a mass range up
to m/z 3000 and is equipped with an electrospray ion source. The
maximum flow rate is 1 mL/min, the optimum flow rate depends on
the application, we suggest you begin with 0.4 mL/min.
Groups that are interested
in using the LC/MS instrument should appoint a group operator. The
group operator will be trained to use the instrument by facility
staff. Once the training is completed, the group operator will be
responsible for training other members of his/her group who wish
to gain access to the instrument. Each research group is responsible
for supplying their own LC-columns. The facility provides the following
solvents: H2O, H2O + 0.05% formic acid + 5%
acetontrile, methanol and acetonitrile + 0.05% formic acid. If you
need other solvents, please feel free to bring your own, just make
sure they have been filtered (0.5 µm filter).
In many cases, buffers
and /or additives are necessary in the mobile phase to modify chromatography.
All commonly used LC/MS techniques require the use of volatile additives.
Use of non volatile additives will cause blockages as the additive
crystallizes out in the LC/MS interface and /or will suppress ionization.
Suitable buffers/additives include formic acid, ammonium
hydroxide, ammonia solution, ammonium acetate and trifluoroacetic
acid. Unsuitable buffers/additives include non-volatile salts
e.g. phosphates, surface active agents/detergents, inorganic acids
(e.g. sulphuric acid, nitric acid, phosphoric acid and hydrochloric
acid). Inorganic acids can cause corrosion of metal parts within
the ion source.
MALDI: Groups
that are interested in using the MALDI instrument should appoint
a group operator. The group operator will be trained to use the
instrument by facility staff. Once the training is completed, the
group operator will be responsible for training other members of
his/her group who wish to gain access to the instrument. Each group
is responsible for supplying their own sample plates (the group
operator will be given one plate at the time of training), matrixes
and other supplies necessary for sample preparation (micropipettor,
micro centrifuge tubes, solvents).
In Matrix-Assisted Laser
Desorption Ionization (MALDI), the sample is embedded in a low molecular
weight, UV-absorbing matrix that enhances intact desorption and
ionization of the sample. Sample preparation is crucial for the
success (or failure) of MALDI. It is important to choose the correct
matrix for your sample as well as paying close attention to the
concentrations of both the sample and the matrix. During training,
the group operator will be given a handout describing the most commonly
used matrixes and how to prepare them.
For questions regarding
the open access laboratory and for training of group operators on
the LC/MS and MALDI instruments, please contact Dr. Ulla Andersen.
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