Solution Stability

[Chris]

I have validated a HPLC assay test method and the samples showed a degradation of 1% over 1 day and 5% over days, therefore I have set the solution stability window as 1 day, however when standards and samples were prepared at the same time the rate of degradation was found to be equal. As many products were being analysed the accuracy run was approximately 48 hours and all accuracy values were within 99 to 101% recovery.

Is it accepatbe to set the solution stability window as 1 day but add a method statement to indicate that as long as samples and standards are prepared at the same time the HPLC run can be upto 48 hours? I would also include a criteria of an RSD of 2.5% or less for the area of all of the standard injections throughout the run to offer some control over the amount of degradation for a long analysis.

Ant comments.

Thanks
Chris

[tom_mizukami]

I think you would be on pretty shaky ground depending on your sample and standard to decompose at the same rate to give you your required accuracy.

I would try to stabilize the compound first; protect from uv, chilled autosampler, etc.

[Lime]

Hi,

May be i got you wrong . But i study solution stability by preperaing std. and sample solutions. Make 5-6 injectios from std. sol. After that making std. and sample solution injections and calculating all of them according to that 5-6 injections i've made before.So, the injections i use for calculating are not degraded and i can see the difference from the starting point.

lime