By Jan on Monday, June 2, 2003 - 11:29 pm:
Dear All,
The European Pharmacopoeia monograph for Acetylcystein uses a C18 column for related substances. The problem is that the first 2 impurities (cystein and cystin) are hardly retained. That's why only 3 % ACN is used (the rest in phosphate buffer). Two other impurities are retained a lot more, but are difficult to separate. As we cannot change any parameters, the only thing we can do is look for a brand of C18 material that retaines cystin and cystein and separates the two other impurities in a reasonable timeframe (20 min). We've tried Symmetry, Bondapak, Prevail, but I'm not completely happy with the separations (resolutions only 1.5 between the impurity-pairs)
Has anyone used this method ?
What column did U use ?
Thanks for your input.
Jan
By A.Nonymous on Tuesday, June 3, 2003 - 12:13 pm:
Normaly you can find this kind of information at:
http://extranet.pheur.org/publications/recherches_sw.shtml
I know, for cysteine there isn't given a specific column, but this is a usefull link for the future.
Maybe you can sent a mail to the European Pharmacopea commision for some more info.
Good luck
By Anonymous on Wednesday, June 4, 2003 - 03:36 am:
Can you please mention the link if available for USP also.
By A.Nonymous on Wednesday, June 4, 2003 - 08:39 am:
I'm sorry but I haven't found the link for the USP yet. But I don't know if it exists or not. In the USP the column is sometimes given in the monograph (like: Chromosil C18 is suitable). So I guess the link doesn't exist. But if so, don't shoot at me.