REG RRF

[chrom]

hi,
iam doing validation for a API, in which Diastereomeric impurity is showing RRF 2.1 with respect to API. My doubt is whether is it acceptable. Because isomer can't be more response.

Thanks in advance.

[tom jupille]

First of all, did you determine the responses using a pure standard of the impurity (I assume you do have a pure standard of the API)?

Second, what, exactly do you mean by "diastereomeric impurity"? Does your API have multiple chiral centers?

Third, what is your chromophore (I'm assuming UV detection), and where is it on the molecule relative to your chiral centers?

Fourth (again, assuming UV detection) is your wavelength set at an absorbance maximum or is it on slope?

[added as edit 1/5/09]. Fifth, how well separated are the two peaks, and are there any baseline or resolution issues that could result in different integration?