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By Anonymous on Saturday, May 29, 2004 - 04:33 pm:
For HPLC Assay determination is it necessary to use a second standard to check the accuracy of the first one, used for assay determination?
If YES, which are the allowed limits for the weight and recovery of the second standard vs. first standard?
Thank you
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By bill tindall on Sunday, May 30, 2004 - 03:21 pm:
In addition to the standards used for calibration it is a very good idea to acquire a large quantity of something that looks like a sample, that is it has the matrix components and analytes at similar concentrations as typical samples and run a sample of this material regularly . Maybe someone else who types faster can tell annon. how to establish control limits from the data collected on this sample......
Such a control sample can detect problems in the method, or how the method is run, that can not be detected with a simple calibration standard.
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By Renata on Monday, May 31, 2004 - 06:14 am:
In every assay I perform, I prepare two standard solutions. One, is 10% higher in concentration than the other. But it's up to you in what concentration the second standard must be. I accept 2% of deviation between the real weight and the result of the analysis.
The purpose is to guarantee the results of your samples and to avoid waste of time. If you have problems with the samples, with just one standard you won't be sure that the problem is really with them.
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By Tim on Tuesday, June 1, 2004 - 08:09 am:
We always prepare a second "check" standard in exactly the same way as the "working" standard and inject it during the initial system suitability. Our requirement is that the standard responses (i.e. Std Area/Std Weight) are within +/-1% of each other.
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By Anonymous on Wednesday, June 2, 2004 - 05:24 pm:
I have an additional question: does the recovery of 2% or 1% apply to pharmaceutical products or drug products?
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By Anonymous on Thursday, June 3, 2004 - 04:32 pm:
Hopefully, neither! I assume you mean %RSD, not recovery.
For HPLC Assay determination is it necessary to use a second standard to check the accuracy of the first one, used for assay determination?
If YES, which are the allowed limits for the weight and recovery of the second standard vs. first standard?
Thank you
-------------------------------------------------------------------------------------------------------
By bill tindall on Sunday, May 30, 2004 - 03:21 pm:
In addition to the standards used for calibration it is a very good idea to acquire a large quantity of something that looks like a sample, that is it has the matrix components and analytes at similar concentrations as typical samples and run a sample of this material regularly . Maybe someone else who types faster can tell annon. how to establish control limits from the data collected on this sample......
Such a control sample can detect problems in the method, or how the method is run, that can not be detected with a simple calibration standard.
-------------------------------------------------------------------------------------------------------
By Renata on Monday, May 31, 2004 - 06:14 am:
In every assay I perform, I prepare two standard solutions. One, is 10% higher in concentration than the other. But it's up to you in what concentration the second standard must be. I accept 2% of deviation between the real weight and the result of the analysis.
The purpose is to guarantee the results of your samples and to avoid waste of time. If you have problems with the samples, with just one standard you won't be sure that the problem is really with them.
-------------------------------------------------------------------------------------------------------
By Tim on Tuesday, June 1, 2004 - 08:09 am:
We always prepare a second "check" standard in exactly the same way as the "working" standard and inject it during the initial system suitability. Our requirement is that the standard responses (i.e. Std Area/Std Weight) are within +/-1% of each other.
-------------------------------------------------------------------------------------------------------
By Anonymous on Wednesday, June 2, 2004 - 05:24 pm:
I have an additional question: does the recovery of 2% or 1% apply to pharmaceutical products or drug products?
-------------------------------------------------------------------------------------------------------
By Anonymous on Thursday, June 3, 2004 - 04:32 pm:
Hopefully, neither! I assume you mean %RSD, not recovery.
