Sodium Metabisulfite HPLC Analysis

[burakayan]

Hello Guys
I am trying do a validation on HPLC. My substance is sodium metabisulfite. I have tried a few methods. My problem is I can't seperate plasebo (novalgin, sodium metamizole) peak from my substance. Retention times of Peaks substance and plasebo are same. I have tried titration and conductivity detection methods but I couldn't get any good results. Can you recommend any other methods?

[Kreall]

Well this is very interesting topic. I can tell you from my and my colleagues experience that you will not get a methed to assay the metabisulfite with metamizol as a placebo. We had this problem just a few days ago and the solution we came up with was that in water solutions metamizol and metabisulfite reacts to form unidentified substance. Also metabisulfide is unstable in water solution. It decays in few hours to form a sulfate and sulfite.
The method we used was capillary electrophoresis to separete anions, and when we spiked standard solution of metamizol with standard solution of metabisulfite, there was no visiable peak of metabisulfite (in retention time of standard solution metabisulfite), only increased peak of sulfates - the product of degradation of metabisulfite.
For my opition your problem proves our theory. It is impossible to separate metabisulfide form metamizol if there is non in your test solution.

[Vlad Orlovsky]

Most likely, you can do this in hydrogen-bonding mode on SHARC 1 column. We have a few water-sensitive methods done in on-aqueous conditions of SHARC 1.
Here is a brochure describing mechanisms and applications, although applications OI am talking about covered by CDA:
http://www.sielc.com/upload/file/pdf/SHARC_1.pdf

contact me by email if you have questions.