Bioequivalence and Bioavailability Forum

Dear ioanam!

❝ … conditions of storage of urine samplings

Ones allowing to obtain valid results for long-term stability (i.e., at least from collection of the first clinical sample to closing of the analytical database)…

Whenever possible you should use PP vials instead of glassware.
You should check in analytical method development whether the compound(s) of interest (parent/meta­bolite) bind to the surface of vials (e.g., some tricyclics stick to PP).
Urine samples freeze much faster than plasma / serum / whole blood does; you have to expect many more brocken glass vials of urine samples. If you have to use glass vials, you should allow for more than usual back-ups (and keep them in a plastic box instead of cardboard).

Dear ioanam,

Just the same way you store your plasma samples !

There is no guideline for this. Common sense says you should follow the storage conditions you have studied during bioanalytical method validation and for which you have demonstrated that your analyte is stable: -20°C, -30°C, -70°C... If you have no validation data yet have a look at available litterature. You have to decide on a case-by-case basis, depending on you analyte and available information.

What may raise problems is also the storage conditions during the collection phase itself. Even though this will only last for a few hours, make sure your analyte is stable under the conditions used (usually +4°C) during the period of collection.

Regards
Ohlbe