EP Mannitol Method

Record: 684

Category: Specifications
Product: SC1011
Sample:

Question
Dr. Ito,

I am currently working on transferring the EP compendia method for Mannitol determination for Ferro Pfanstiehl Laboratories and am interested in some information regarding column SC1011-7F.

I have tried different manufacturers’ columns and keep seeing negative peaks in the blank injections, one of which is almost exactly the same retention time of Mannitol. These peaks have a negligible effect on the assay determination, but significantly effect the limit and limit-of-quantitation injections – Reference solutions B & C according to the compendia. I have tried a number of solutions, in regards to systems and mobile phase (water) treatments, to either get rid of the negative peaks or adjust the retention times.

I have seen the chromatograms on the Shodex website for Mannitol and its related substances. My question is whether these peaks have been seen using the SC1011-7F or SC1011 columns, and if it would be possible to obtain a chromatogram of a blank injection on-scale with the related substances to see this?

I would like to know if there is potential for the same problem to exist before I purchase columns.

Answer
The lab in Japan does not have a chromatogram for the blank, but attached chromatogram may give you some idea.
At 85 oC condition, a small negative peak is observed before mannitol.
If you could give us some more time, the lab is willing to take a blank chromatogram for you.

The negative peak in your chromatogram does seem big. Are you using a degasser? Even so, if degasser is not working properly, or if there is any loose point in connection parts, you may observe such a large negative peak. We would recommend you to check this possibility also.

 
 
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