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The ICP serves as a primary elemental analysis instrument for Stanford
University community. Anyone
planning to run samples should sign up here on this web site first before
bring samples in for analysis. First time users should
contact lab personnel first by email
before sign up for analysis.
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Operation: The ICP is operated only by appointed personnel. No users are allowed to
operate the instrument or computer without the approval from the operator. Please direct any
questions to us.
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Samples: All samples for analysis must be in aqueous form. Unknown samples and
standard solutions must be free of solid particulates.
Samples should be filtered with a 0.45mm or smaller membrane filters. Solids in the samples
can cause inaccurate
readings and clog the nebulizer, resulting in longer running time,
expensive repairs, replacements, and down time on ICP which we would like to avoid.
Please note that we do not digest samples for users but we may provide
information on it.
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Standard Solutions: The standard solutions should be prepared by the users in the same
matrix as the unknown samples. Prepare your standards carefully
because it will affect the accuracy of your results. Inaccurate high
standard solution and contaminated blank can result in inaccurate results for
your unknown samples. In addition, if you give
us an inaccurate quality control, it will fail more often and cause the whole
process to take longer, which will cost you more.
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Cost: Because the ICP has a high maintenance expense we
have to charge users for using it, however, since this is not a commercial lab
instrument, the charge is minimal for our users.
Currently, we are charging per time used and the minimum charge is 0.5 hour.
After that the charge increment is 15 min. Please check this link for
current rate. Users are charged for a
minimum 30 min. warming up time plus the actual time used to run samples.
When you sign up for using ICP, a valid PTA number has to be provided
online for running samples.
The ICP operator must be provided with:
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A Blank—this is your matrix solution, 100 ml is sufficient
in most cases.
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A High Standard (Hi Std)—all elements that are going to be measured
must be
included in this solution. The concentration of high standard should be higher than the
concentrations you expect from your unknowns but not too much higher than it. Minimum volume should be 100 ml.
For first time users, this should be 250 ml at least since a new method
needs to be developed. This solution should be made with the matrix
you used for your unknown samples if possible.
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A Quality Control Standard (QC)—this solution is again all elements
in one solution, but the concentration is somewhere between zero
and your high standard. The preferred concentration should be 1/2 of
your high standard concentration. If you have 100 or fewer samples, please provide
100 ml of QC. If you have more than 100 samples, please provide 250 ml or more.
Blank, Hi Std, and QC solutions should be brought in what ever the
containers you are using. They do not need to be placed in the 13X100
test tubes.
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Unknown samples-
All unknown samples must be contained in 13X100 mm test tubes, which will fit
to the ICP autosampler rack. There are two types of test tubes to use:
plastic and glass. They can be obtained from Fisher Scientific or your
preferred vendors. For your convenience, here are the cat #s for buying
from Fisher
Scientific, 14-961-24 for glass and 14-950-8E for plastic. Do not use
other smaller tubes since they will damage the autosampler. Eight(8) ml of samples should be enough.
Please contact us if you do not have enough solution.
If you have any questions making standard solutions, please check with Guangchao Li at gcli@stanford.edu or call
724-3220.
Data: After analysis is complete,
users need to come to collect all standard solutions and unknown samples left
from the run immediately. Then, the data will be posted on our web page and you
will be able to download your data from our website. Click on
http://em-1.stanford.edu and follow the link to Download Data. Your data file will be listed in your group
folder, which is named after your PI's last name and data filename is made up of your initials and the date your samples are analyzed,
e.g. JH060606.txt. After you save the file on your hard drive, the
data file can be opened by spreadsheet programs such as Lotus, Excel, or Quatro
Pro. All data collected from the ICP will be saved for at least 30 days. Files
older than 30 days may be deleted to make space on the hard drive if needed.
More
information about ICP-AES analysis from EPA.
You can get more detailed information by checking out our
FAQ.
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