During the average study, it is likely that the samples may experience several freeze-thaw cycles, and it is important to know the sensitivity of the analyte to degradation resulting from this type of handling. This effect is assessed by assaying spiked samples after three freeze-thaw cycles. Study samples should be frozen for a minimum of 24 hours (at the temperatures planned for storage in the clinical study), then thawed at room temperature. Once completely thawed, the samples should be refrozen for a period of 12-24 hours. This cycle should then be repeated twice or more, and then the samples should be analyzed. Low and high concentrations of the drug should be assessed in triplicate.
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