The following guidelines should be used when samples are submitted for analysis in the IUMSC. While most of these rules are common sense, an attempt has been made to explain the rationale behind each rule.
MSC Sample Identification Number.
Each sample is assigned a reference number upon submission. This number is on the "sample submission form" that you must fill out and leave with the sample. This number must be affixed to each container submitted (nmr tube, vial, beaker, etc.). It is all too easy to confuse samples when they are not clearly labeled with the assigned number. You should record this number in your lab notebook and always refer to it when making any inquiries about the status or results of the analysis.
Sample Submission Form.
Sample submission forms are available in the IUMSC. Please use one of the pre-numbered forms, and fill out carefully and completely. Please note the following:
- Print your e-mail address clearly. This is how you will be notified of the status of your sample.
- When entering the empirical formula, enter in the order carbon, hydrogen, followed by other elements alphabetically placed. For example, C32H14Br2Mn4N5O12. If you do not know the exact formula, make an intelligent guess! DO NOT use abbreviations in the empirical formula line, use them in the space for the suggested structure.
- List the solvents used.
- List any special environmental precautions that we need to be aware of (odor, toxicity, etc.)
- Check the appropriate boxes if special handling is required (inert atmosphere, etc., see below).
- Enter the account to be charged. It is assumed that you are authorized to use the account listed.
- Never remove a Sample Submission Form from the IUMSC. If you wish to withdraw a sample, write "withdrawn" on the existing form and let the staff know.
Handlings of Samples.
Common sense dictates most of the following. The quality of any structure determination is dependent upon the quality of the crystal. A common error is submitting crystals that were grown in haste. While data from marginal crystals can easily determine the connectivity, a poor crystal may yield results that cannot be published.
- Where to leave Samples. Samples should be left in the IUMSC with the sample submission form. If the sample requires special handling (i.e. storage in a freezer), talk to one of the staff members and be sure to indicate the location on the Sample Submission sheet.. If there is some reason why the sample cannot be left in the IUMSC, you must make prior arrangements with one of the staff members. The order in which samples are run will is determined not by when the form is filled out, but by when the sample is actually submitted.
- Air Sensitive? Any sample that is expected to be problematic because of reactivity (air or moisture sensitive for example), should be submitted in more than one container. Remember that there are surcharges for special handling. Any information you can furnish will assist the crystallographer in obtaining the best possible results.
- WHY NOT BE SAFE AND SAY EVERYTHING IS AIR SENSITIVE? While this might seem to be a conservative approach (assuming the surcharge doesn't bother you), it can certainly be detrimental to a quality analysis. Why? If the user indicates that a sample is very air sensitive, we make every effort to remove the sample from the container, mount it, and transfer it to the cold stream as rapidly as possible. The inert atmosphere techniques we use are good, but not perfect. The plastic glove bags simply cannot be sealed as well as well as the inert atmosphere systems the researcher has available. Because of the rapid transfer, the crystal selected may not be the best available.
Furthermore, if the crystal selected is found to marginal in quality, we may decide to collect data anyway, since the bulk of the sample may have decomposed in the glove bag. Removing the "marginal" crystal to look at another sample would result in the loss of possibly the only crystal available. Note that most of the stability problems can be eliminated by submitting the sample in more than one container!
- Sample Container. If the sample is air sensitive and requires inert atmosphere techniques, be reasonable about the container it is supplied in. We have had some samples submitted in specialized glassware that was nearly one meter in length! The glove bag system we normally use can easily handle small glassware only.
- When we are done.... Please be good citizens and pick up the remainder of your sample. Larger research groups are encouraged to appoint someone to occasionally check for glassware etc. left in the IUMSC. Any samples left after a reasonable amount of time will be discarded.