Precision and Accuracy

[ananda]

Hi All,

If one has done the precision and accuracy in an HPLC method validation by 6 replicate injections from the same sample (from the same vial) is it not acceptable and against the ICH or FDA guidelines?

Is it has to be a single injection from 6 deifferent sample preps in 6 different vials??

Thanks in advance.

Ananda

[syx]

For accuracy, single injection from 9 different sample preps (3 conc level, each 3 samples) in different vials.

For (intermediate) precision, single injection from 6 different samples preps in 6 different vials for each analyst, in different days, instruments, etc.

[ananda]

Hi Syx,

However according to ICH Q2B, Precision -Repeatability should be done as follows:
"A Minimum of 9 determinations covering the specifiied range for the procedure (eg. 3 concentrations/3REPLICATES each)"


Ananda

[Rick Jagielski]

Hi,

For exactly what is required I refer to this page:
http://www.fda.gov/cder/guidance/cmc3.pdf

It breaks it down pretty well although it is not exactly all inclusive it does give you an example of what is acceptable.

We usually do three different tests to demonstrate accuracy and precision.

"Injection precision" is done by taking replicate injections from the same vial. This demonstrates that the instrument can perform the test in a repeatable way. Usually the %CV of the response from these injections needs to be less than a specified amount.

"Intermediate precison" is done by having at least two analysts perform three assays in triplicate on the same sample. At least one of the assays must occur on a different day, and if you have multiple systems in your lab it is preferable to use a different system for one of the assays. (Since GLP guidelines indicate that analysis be performed in triplicate this would equal 9 individual sample vials)

Accuracy is demonstrated using "Spike Recovery" This involves aquiring a placebo or blank sample. Extract an amount of blank that would be appropriate if it was at the target concentration, add the analyte in such a way that the concentration can be quantitatively determined. We test at 80% 100% and 120% of target value with three determinations for each concentration level. Run the samples and see what value is determined (actual/theoretical) Your lab needs to specify what recovery range is acceptable.

Hope this helps and I wasn't too long winded

Rick

[ananda]

Hi SYX and Rick,

Thank yo very much for your comments. I agree with both of you that specially for preciosion there are 3 sub-items to be checked such as inter-day precision and reproducibility etc.
Thanks again . The CDER document is a good one.

Regards!

Ananda