Chromatography Forum

I am conducting an informal survey. We have a procedure, in a pharmaceutical lab for running 5 replicates (usually) of a standard to get the % RSD and then reinjecting the same standards in duplicate throughout the run and have our own acceptance criteria throughout the run. Can anyone share what their labs ordinarily do and what the acceptance criteria are? I won't tell you ours because I think that it is not proper.

Thanks

For 1 level esternal standard runs:
5 or 6 replicate standard injections at the start of the run help determine initial system suitability.
After each sample group, one or more standards are injected (commonly 3). The average of all standards is used for calculations, provided that they meet the same RSD criterion as the initial group did. If the entire set does not meet that criterion and there are no obvious causes to be assigned, we go with nested bracketing. Each sample group's standard injections (before & after group) are evaluated (hence the use of 2 or 3 between groups). Where the standard groups meet criteria, groups are accepted. Where standards fail to meet criteria, groups are reinjected (or reprepareed & run vs. fresh standard depending on how old they are).

5 replicate injections in the beginning (Std A) followed by a single injection of a separately weighed std (Std B).

A single inj of Std A after 10 samples, and at the end.

As far as acceptance criteria - I'll show you mine if you'll show me yours

Six injections of one solution to confirm meeting requirements, then 3 different standard concentrations initially in duplicate and one standard in duplicate every 10 samples, with all standarda in duplicate at end.
Use the average response factor, and acceptance criteria depends on method, as many of active compounds are only at stage I and II.

Interesting to note that USP canned some part of their new system suitability criteria that was supposed to be effective at the beginning of this month. Must try to take a peak at a copy sometime...

http://www.usp.org/USPNF/notices/postpo ... er621.html

Please keep having fun,

Bruce Hamilton

We follow the following inhouse procedure:
- 5 std injs at the start of the run (%RSD = n.m.t 2%)
- 2 std injs after every 12 samples
- overall RSD of all stds = n.m.t 3%.


I hope this helps.
Mike