Suggested practices are noted in the following sections with little support other than being common practices that do not appear, in general, to be problematic. If deviating from these suggested practices with longer storage times or different temperatures, it would be important to assess whether more extreme storage practices will have an impact on the samples. This is essentially a validation of the user's practice. However, getting less than detectable values for both analyses does not "validate" the user's more extreme storage conditions. Non-zero values are usually needed from both analyzed samples in order to confidently "validate" the user's storage practice. If sample storage practices are within the guidelines established, then it may not be necessary to validate the practices.