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So does anyone KNOW, and can link/provide official source for this RSD limit? Thanks a lot.
Off-topic conversations and chit-chat.
shepchemalum wrote:
according to USP 37, in the volumetric solutions section there is this:
1.3 Correction Factor: It is frequently difficult to prepare standard solutions of a desired theoretical normality or molarity, and this is not essential. A solution of approximately the desired normality or molarity is prepared and standardized by titration against a standard. The correction factor so obtained is used in all calculations where such solutions are used. If necessary, the concentration of the solution may be adjusted to a given normality or molarity, by dilution or by addition of the appropriate reagent.
The concentration of the volumetric solution does not differ from the prescribed one by more than 10%. The correction factor is determined by an appropriate number of replicates. The repeatability does not exceed 0.2% (relative standard deviation). The correction factor should be redetermined frequently.
This is what we use as our limit.
KM-USA wrote:shepchemalum wrote:
according to USP 37, in the volumetric solutions section there is this:
1.3 Correction Factor: It is frequently difficult to prepare standard solutions of a desired theoretical normality or molarity, and this is not essential. A solution of approximately the desired normality or molarity is prepared and standardized by titration against a standard. The correction factor so obtained is used in all calculations where such solutions are used. If necessary, the concentration of the solution may be adjusted to a given normality or molarity, by dilution or by addition of the appropriate reagent.
The concentration of the volumetric solution does not differ from the prescribed one by more than 10%. The correction factor is determined by an appropriate number of replicates. The repeatability does not exceed 0.2% (relative standard deviation). The correction factor should be redetermined frequently.
This is what we use as our limit.
Great. I hadn't noticed the change in that Chapter from USP 36 to USP 37, but it is there. But it really isn't there, it's in the section for correction factor, not in standardization, so confusing. Very confusing.
But, question: does your lab have any difficulties meeting such tight 0.2% RSD limit? That does seem awfully tight. Also, USP states "appropriate number of replicates" - so what exactly is this? 3?
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