Microanalytical Laboratory

SAMPLE PURITY:

The determination of the concentration of elements in your sample is based upon the direct weight  of the the material sampled.  Therefore, it is very important that samples be dry, free of foreign substances such as dust, rust, hair, aluminum foil, parafilm, and paper filter fibers ( the most common contaminant).  Microscopic inspections have shown that over half of the samples submitted are obviously contaminated.

Most journals require   0.40% for each element. For comparison, NIST standards are   0.03%.  Typical compounds submitted have errors ranging from   0.05% to 0.45%.  These compounds have all gone through several stages of purification. Let's say while putting your sample into a vial a spec of graphite from your pencil fell into the vial and blended in with your yellow crystals.  Let's also say that the spec of graphite weighs 100 µg ( that's really a large spec by the way). The nominal sample size for CHN is 2000 µg.  If the spec is taken as part of the sample, then there is a 5% error in the weight. So you see, it doesn't take much to throw the result off. 

SAMPLE SIZE:

The actual amount of sample needed depends on the concentration of elements to be detected. To avoid confusion, listed below are the requirements for minimum amount of sample needed per analysis.

NOTE:  THE WEIGHT LISTED IS THE AMOUNT THAT MUST BE REMOVED FROM THE SAMPLE VIAL - NOT THE AMOUNT PUT INTO THE SAMPLE VIAL!

Again, these are the minimum sample sizes needed. It is in the users' best interest to submit enough sample for duplicate analyses. Occasionally analyses will be repeated to verify results.

Even though there is a sample disposal fee for OUTSIDE samples, OUTSIDE  users should still submit extra sample since there will be a disposal fee even for empty bottles.

SPECIAL NOTE FOR AIR SENSITIVE CAPSULES:  Since the lab has no feasible way of extracting extraneous sample, it is important to put  in as close to the minimum weight  as possible.  Only analyses for metals can be diluted.  In other words, CHN or HALIDES analyses of overfilled capsules could lead to erroneous results.  Lettered bottles are for CHN's.  One capsule should be submitted for each determination - HALIDE, METAL, or  CHN.

SAMPLE CONTAINERS:
Containers should be clean and all surfaces inert to your sample.

All containers must have the backside of vial free from tape or other label material.  It is best to write on surface with Sharpie marker, or apply sticker to cap.  It is important to have sample ID on sample container.  Sample ID should follow this format:  initials - ###A  (Ex. = JL - 123A)

Outside users should follow same ID format but also include School initials & advisor's last name.  (Ex. = JL - 123A  MSU - Johnson  or    JG - 047C  UK - Smith)  These should also be placed on your sample submission card to avoid mixing of samples.
 

SUBMISSION  RECORD  CARD:

Self-carbon cards are available for submission and reporting results. The top copy stays with the lab and the bottom gets returned with results. Alternately, submission cards may be printed from the web and then filled out in duplicate (submission record card pdf file). It is extremely important to label submission record card identically to sample vial.  For sample ID format SEE SAMPLE CONTAINERS.

It is not necessary to have the exact theoretical percentage of each element listed.  It is crucial to have listed at least a range or approximate value in order to calibrate the instruments.  We don't need to know what the structure looks like in 3-D, but we would like the formula (even if its a guess).  Once again, some compounds need to be treated differently (e.g. inorganic vs. organic).  The lab needs to know if and what metals, halides, or other interferences are within the sample.  It is also a good idea to record the physical state of the compound at submission (e.g. color, crystal, liquid, mp, and molecular weight)

SAMPLE  DROP  OFF

Samples can be brought to 47 Noyes Lab  and placed in the appropriate service tray. Samples that require multiple services should be placed in the service tray to be performed first. Samples that are moderately sensitive should be placed in the appropriate container such as vacuum desiccator, regular desiccator, high humidity container, or freezer. (The freezer is maintained at just above 0 °C).  Mark on submission record card where sample is located.

Outside users or users outside of Chemistry can mail their samples in protected containers to:

Rudiger Laufhutte
Microanalysis Laboratory
School of Chemical Sciences
University of Illinois, Urbana-Champaign
47 Noyes Laboratory, Box 59
600 South Mathews Ave.
Urbana, IL 61801

UNSTABLE SAMPLES:

Some samples may remain at room temperature as submitted for 0.5 to 24 hours before an analysis is started. If your sample is unstable there are several steps that can be taken to avoid agony in the results. (SEE   SPECIAL   NOTE below)

1. Submit sample in air-sensitive double vialed capsule. (Sn for CHN;   Al for METAL /HALIDE) Once the capsule is taken out of the vial, it is only protected as well as the seal made on the capsule. Make sure capsule is sealed and folded over. (SEE picture next page)
2. Leave sample in desiccator or freezer. (mark on submission record card where sample is located)
3. Submit sample vial inside a larger vial that is partially filled with Drierite and has wool keeping any possible specs of Drierite away from sample vial.
4. For extremely sensitive samples,make an appointment for drop off of sample for processing immediately.

SPECIAL NOTE FOR AIR SENSITIVE CAPSULES:  To use air-sensitve bottles, take the appropriate one from the shelf located just inside the lab.  Fill the capsule and crimp it in your dry box.  After crimping gently place a fold in the crimped section to form a good seal.  Reseal in both vials.  Drop off bottle in vacuum desiccator and write down bottle letter and/or number on submission record card.  There are a limited number of bottles for air-sensitve samples.  Be considerate of your fellow researchers and take a bottle only if you are going to be submitting a sample in the next couple of days.  If a bottle gets broken, please bring back the remains and let us know which bottle and if the capsule has been contaminated.