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- Posts: 104
- Joined: Sun Sep 13, 2015 7:54 am
I was running an impurity analysis on a technical grade material of L-Carvone - 10 separate batches with purities ranging from 93.00% to 99.27%.
The technical grade material is synthetically made and I would image that if I have a purity of 93.00%, there should be a significant amount of other "stuff" compromising that 7% that I would detect on the mass spec.
Specifically, the supplier does their own analysis and usually finds the following impurities: dihydrocarvone, carvenone, and cyanocarvone. They are found at concentrations between 0.01 to 0.3% depending on the impurity.
Now, when I look at these molecules, they are very similar to my main compound in structure and have very similar physical properties. My question is sort of general - mass spec is my weakest subject - but if I am unable to separate these impurities from the main compound on the column, and they elute into the mass spec at the same time, will the sheer higher relative concentration of the main active ingredient "overshadow" the fragmentation spectrum of these other possible impurities? My chromatogram only shows one peak but the fragmentation ion spectra at different parts of the peak look slightly different but not enough to give me a different match in the library.
Due to time constraints, I was forced to follow the method supplied by another lab (column, parameters, etc... were all identical to what they ran). I have a feeling the column I am using, ZB-FFAP is not able to separate these molecules on the column properly. I find it very strange that I see only one peak on my chromatogram when the supplier (not the supplier of the method, but the chemical supplier) has shown impurities up to 0.3%.
Thanks for any help!