Chromatography Forum

Hello,

if i want to perform qualitative analysis on a raw material with USP method, how can I perform specificity and system suitability test? for Quantitative i got that I have to use a placebo to rule out the interference but what do I do if its for ID testing only.

Please advise.

Thanks!

Same thing.

But what would be a placebo for a pure raw material - f.x. 99.8% acetic acid or whatever?

It might be adequate to inject the sample solvent/diluent - f.x. water which typically is done annyway - the blank sample.

Hi Danko,

USP recommends injecting (standard) compounds having similar structures to the raw material whose identity is to be confirmed via the completed method during method verification/validation to serve as a demonstration of Specificity.

There's always something....

Hi mattmullaney,

Placebo is something completely different from what you describe. In cases where one loads placebo solutions in order to eliminate formulation interference there is an active subsance and formulation matrix. So the placebo would be the matrix without the active substance.
In raw material cases where the compound constitutes the sample nearly 100% you can not speak of placebo.

Best Regards

Hi Danko,

Thank you--to clarify what I meant, in the case of validating/verifying an HPLC method for the Identification of a Compound (the qualitative analysis of not only an active substance) Without a Matrix, USP encourages demonstration of the separation of the compound of interest from compounds having similar structures to indicate a degree of Specificity.

Agreed, it's pretty hard to have a matrix where the substance to be determined is highly pure, to begin with.

Then you'll need a pure raw material with a similar structure. For your example of acetic acid, you'd use formic acid or propionic acid.

Hi again, Rndirk,

Agreed again--assuming that the Original Poster, mitalp, is working with the goal in mind of keeping with USP's recommendation.

Provided we are done discussing placebo because of no relevance in the case, attention should be directed to possible impurities when documenting method specificity.
There are 2 types of these.
1. Syntesis impurities (leftovers from the materials uttilized in the production.
2. Degradants.
The latter is possible oxidation, deamidation and whatever products one would expect based on studies and/or theoretical knowlage.
One should be able to separate these and ideally quatitate them.

Best Regards

Thank you everyone for the responses, I really appreciate everyone's time efforts. I am new here and wasn't sure how to use this forum but now i know.

Question regarding similar structure for my active ingredient, I work with dietary materials so it is tough to find the similar structure ingredients. is there any source where we can search for similar ingredients structurally.

thanks,
mitalp

Hi Mitalp,

Sometimes the FCC (Food Chemicals Codex) may help, more rarely USP may provide guidance here for materials to use in the determination of method specificity. Occasionally the vendor is able to help as well--that is, the vendor of the raw material in question--or companies such as Millipore Sigma.

EDIT: the website chemexper.com may also be of help here, perhaps more so than the FCC.