RE: RE: RE: Reference Std. Contribution from Lance Smallshaw written on 6/27/2008 at 06:48
Original contribution: RE: RE: Reference Std. written by Ana Madrid on 6/26/2008 at 13:50) Hi Ana, I'm not quite clear here by the '5ug' compendial std. If you mean that your test method requires you to prepare your test concentration to 5ug, and your national requirement to establish a secondary standard is to test 4 primary standards to every secondary standard, then yes you will have to prepare 4 primary std vials at 5ug and 1 secondary std at 5ug? The DOE when establishing an in-house std (secondary std)must take into account vial to vial variability (and henceits preparation) of the primary std into account. On the other hand,if you mean you need to use 4x 5ug replicate std test preparations throughout an analysis run for example HPLC run, for every 5ug secondary std test preparations then you can dilute a single vial of primary std but again your std establishment protocol and hence your DOE must take in account vial to vial and therefore preparation to preparation variability and ideally for e.g. potency assay, intermediate precision considerations. Answers to this contribution:
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