Method Validation using 2002/657/EC (CCa; determination)

[vishal_aes]

We are currently working on in-house method validation of chloramphenicol in milk using LCMSMS. We are carrying out validation as per 2002/657/EC. Can some one assist me in estimating CCa (decision limit) ??

[dr_Pyrex]

You can find lots of interesting publications in this topic, just use pubmed.gov and search for "chloramphenicol 2002/657/EC". If you want use some "validated" software for it, you can buy cheap (about 100 Euro) ResVal - excel-based software from Community Reference Laboratory in Netherlands:
http://www.rivm.nl/bibliotheek/digitaal ... n2006a.pdf

[vishal_aes]

dr_pyrex, thanks for the information. I am using the calibration curve procedure and I am a little confused as to how one calculates the standard deviation of the within-laboratory reproducibility of the intercept. I have figured out he rest except this. I will also find out about the excel program in the meantime, thanks

[carras]

Our lab has been grappling with 2002/657 for some years now and I can tell you it is not easy. We have several methods accredited under ISO 1725 and I can assure you my auditors are as uncertain as me as how to calculate a meaningful CCalpha.
We also use the calibration curve but only to get an idea of the actual value of CCalpha. Then, we check this theorical value in terms of unequivocal identification: if this CCalpha is true about half of the samples spiked at this concentration should be "compliant" (e.g. "not detected") because their ion ratios are outside the range allowed in the Decision, which implies there are not enough identification points to identify the analyte. If that is not the case we try higher or lower concentrations until we get around 50% compliant samples.

Hope it helps. Good luck