Elemental Analysis Sample Submission
Sample Submission Form
Please use this "Sample Submission" form, in Excel format. Using this enables us to more efficiently acquire and process your data. Up to eighteen samples can be submitted on each form. Download the form to your computer and fill it out electronically. Sample ID's must be kept very short, typically 4-6 alpha-numeric characters. You MUST e-mail the completed Excel version of the form before or when you submit your samples.
Instructions for Submitting Stable Samples
The schedule may vary depending upon the work hours of the undergraduate assistant who weighs the samples. Generally samples must be submitted by noon on Tuesday in order to be run that week. Samples are normally run on Wednesday or Thursday; expect the results to be emailed to you by Friday. Remember to retreive your unused samples, otherwise they will be disposed.
- If less than five samples are submitted for CHN (or five samples submitted for CHNS), the weekly run may be canceled. Speak to me in advance if you have special needs.
- Approximately 2-3 milligrams of sample will be combusted in each run, and samples are typically run in duplicate or triplicate. Therefore, samples should be submitted in quantities of 8-12 mg in order to ensure that sample transfer can be accomplished easily. The physical nature of your sample and the vial will determine this. You may retrieve your excess sample when the analysis is finished.
- Samples must be completely pure and completely dry. It is preferable for you to powder your sample rather than submit large "chunks".
- Oils, pastes, and liquids can be accommodated with some difficulty. Submit considerable excess.
- Please list any special combustion conditions for your compounds referenced in the literature or in technical notes. Un-referenced comments will be ignored. The default combustion conditions should work for greater than 90% of all samples.
- Unexpected results based upon only one sample run will not be discussed. Two runs are required to verify the precision of the measurement.
- The CHNS combustion tube is used by default. However, an accurate Sulfur % requires the addition of vanadium pentoxide, so please note on the sample form if you require S. You will get a S % by default, but that value may not be reliable without the addition of vanadium pentoxide. CHNS runs take 720 seconds for each sample.
- The CHN combustion tube may be used in situations where a shorter analysis time is required. However, the CHN combustion tube requires the use of a different GC column, so switching will only take place once a month. The CHN run time is approximately 450 seconds.
- It is not necessary to tell us the formula of your sample; it can be treated as an "unknown" if you wish.
Please feel free to discuss your project with us at any time.
Instructions for Submitting Air Sensitive Samples
There are two submission procedures we recommend for air sensitive samples; the choice depends upon your assessment of the stability of the sample.
Type A. Samples that are Stable in Air for at Least Five Minutes
These samples should be submitted in multiple small vials. For two runs per sample, split your sample between two small vials. In your glove box, load plenty of the sample (at least 10 mg) into each vial. Cap the vial. Although we will only use about 2 mg per run, sample transfer and weighing can be done much more quickly if there is excess sample in the vial. Be sure that your sample is a fine powder. This will avoid us having to spend extra time crushing the sample before we weigh it. Once you have loaded your sample into vials, place each vial inside a larger bottle, preferable with a drying agent. Cap the bottle. This should also be done inside your glove box.
When you submit your samples, clearly label them as Air Sensitive – Type A on the submission form. As long as both the vials and the larger bottle are filled with inert gas (typically nitrogen, helium or argon) the samples should be stable, however you could, at your discretion, notify me that you would like to submit Type A air sensitive samples so that we can coordinate our analysis schedule with your sample submission.
Type B. Samples that are NOT Stable in Air for at Least Five Minutes
These samples need to be loaded into small pre-weighed tin vessels. These should be requested from me several days in advance. NOTE: Because of the weighting procedure used, please do not use pre-weighed vials left over from previous runs. Request new ones. You will receive small numbered vials with one tin vessel in each vial. The tare weight of the tin vessel may or may not be marked on the small vial. Don’t worry if it is not. You will also be given one larger glass vial for each small vial. These are not numbered and can be used interchangeably. Inside your glove box, you will load approximately 2 mg of sample into each tin vessel, then crimp and fold the tin vessel in the manner you have been taught and have practiced. It is important that you have a balance inside your glove box in order to roughly weigh the amount you are putting into each tin capsule. Weights may range from 1.5 mg to 2.5 mg.
Place each folded and crimped tin vessel into its numbered small vial. Cap the vial. Don’t get them mixed up, or the weights will not be correct. Then place each small vial inside one of the interchangeable larger glass vials. Cap the vial. Use a permanent marker to label each of the vials or vial caps. All of this should be done inside your glove box.
When you submit your samples, clearly identify them as Air Sensitive – Type B on the submission form. As long as both the small vials and the larger vials are filled with inert gas (typically nitrogen, helium or argon) the samples should be stable, however for Type B air sensitive samples you MUST notify me that you would like to submit air sensitive samples so that we can coordinate our analysis schedule with your sample submission.
The sealed tin vessel will be exposed to air for about sixty seconds during the final weighing process. As long as the tin vessel has been properly crimped and sealed (without any cracks or tears in the tin) we will have an excellent chance of getting good results for you.
You will need to practice loading samples into the small tin vessels. Using any powdered sample, practice loading, sealing, and crimping the tin vessels on your lab bench. Obviously you do not need pre-weighed vessels for practicing your technique. Next, practice your technique working inside your glove box. Only when you can consistently load, seal and crimp tin vessels while working inside your glove box should you begin loading your air sensitive samples into pre-weighed vials for analysis.
A number of small tools including tweezers and spatulas are necessary. You may borrow ours if you ask for permission.