Stability postpreparative

Postpreparative Stability. The stability of processed samples, including the resident time in the autosampler, should be determined. The stability of the drug and the internal standard should be assessed over the anticipated run time for the batch size in validation samples by determining concentrations on the basis of original calibration standards. Reinjection reproducibility should be evaluated to determine if an analytical run could be reanalyzed in the case of instrument failure. 

As demonstrated by many studies, SIL internal standards outperform structural analogue internal standards in terms of precision and accuracy provided the extraction and LC separation are comparable [8, 25-30], In addition, SIL internal standards can also extend linearity range, enable the usage of less reliable transitions (e.g., loss of water), and prolong in-processing and postpreparation stabilities [8, 28],... 

Sample stability 3x Freeze-thaw cycles for samples between -70 °C and room temperature 4-24 h at room temperature long-term storage sample stock and postpreparation stability. 5-10 ng/Lx6 at <6 °C for 28 days NA 3x Freeze-thaw cycles for samples between -20 °C and room temperature Ambient and 4 °C for 7 days... 

AU stability in matrix and in reconstituted sample extracts (postpreparative stability or autosampler stability) should be assessed at least in three replicates and at two QC, that is, LQC and HQC concentration levels. 

Postpreparative Stability (Autosampler Stability) Stability of processed samples should be determined at the autosampler temperature that will be used during study sample analysis and for a duration of time equal to or greater than the batch size expected to be used for routine study sample analyses. If sample extracts are to be stored (e.g., in a refrigerator or freezer) before analysis, then the stability of the analyte in the reconstituted sample extract under these conditions should be investigated. In postpreparative stability assessment, the mean concentration value obtained from each QC concentration level after storage in autosampler is compared with the respective nominal concentration value. The mean bias (%) between the values should be within +15%. If the stability is demonstrated, then an LC-MS/MS run can be restarted after an unexpected interruption as long as system suitability has been established and documented. 

Tables summarizing results for all stability experiments conducted in the validation should be provided. These may include bench-top, freeze-thaw, long term, stock and postpreparative extract stability. Example tables that can be used for freeze-thaw stability and stability in matrix at room temperature are shown in Tables 10.4 and 10.5.

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