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FAQ

faq

How much sample is required for my analysis?


Each CHN analysis should include at least 5mg of transferable sample. Halogens depend upon the theoretical percentages expected.

% expected %Cl %Br %F %O %P %I
1-5% 25 mg 10 mg 20mg 20mg 4mg 5mg
5-10% 10mg 5mg 10mg 10mg 3mg 4mg
10-20% 5mg 3mg 10mg 5mg 3mg 3mg
above 25% 4mg 2mg 10mg 4mg 2mg 3mg

All sample sizes are meant as transferable from the vial.

 

Is it important to list theoretical percentages?


It is most important that submitters list a molecular formula. This allows us to rule out interferences as well as select the optimal sample size for highest accuracy. If mistakes are made due to lack of input on this matter, there is an additional charge for rechecking results.

 

Can you provide RUSH service for my sample?


Yes we do. We ask that submitters limit RUSH requests to 2-3 samples. Rush analyses must also be limited to CH, N, Cl, S, and Br analyses. These samples should be finished within 8 hours. Please note that samples with fluorine, oxygen and phosphorus normally cannot be completed within 8 hours.

There is NO ADDITIONAL CHARGE for this service.

 

Do you handle air-sensitive samples?


Yes we do maintain a glove box. There is an additional charge of $25.00 for special handling under argon. Samples should be sealed adequately when shipped. Air sensitive samples must be transferrable. Heavy thick oils cannot be transferred adequately for this type of analysis. Due to techniques used, we cannot analyze sulfur on an air sensitive substance. Drying is never done on air sensitive samples. Samples with extremely strong stench should be noted as so.

 

Are there any specific types of samples that you do not handle?


Yes. Due to the health and safety of personnel, we do NOT handle any compounds containing Osmium, Uranium, Thallium. Samples with extremely high toxicity and extremely strong stench we no longer analyze. We do not handle any Finished Pharmaceuticals for release. Highly volatile liquid samples with very low BP (less than 40 deg C)

 

How did you perform the analyses?


CHN analysis is performed via combustion at 990 deg C with the elemental analyzer.
Sulfur, Chlorine,Bromine and Iodine are done via flask combustion and subsequent titration.

Oxygen is done by pyrolysis at 1200 deg C and determined gravimetrically. (Unterzaucher Method).

Oxygen determination is done on purely organic substances only (no metals or phosphorus present).

Fluorine is done by bomb digestion and subsequent determination by ISE.

 

Do you perform organic trace analysis?


No we don’t. Phone us if you have a need for this. We can recommend a qualified laboratory for this service.

 

Do you offer discounts on your current fees?

Yes we do offer discounts based upon monthly sample volume. Phone us for details.

 

Are samples returned?


Yes, all samples are returned via USPS for the cost of postage. We do not dispose of chemical samples.

 

What Organizations do you belong and what Licenses do you currently maintain?


Midwest Microlab is licensed with the USDEA to handle all controlled substances Class I thru V.