Upon receipt, frozen FBS should be immediately moved into a -20°C (or below) freezer and protected from light; it should not be allowed to thaw until ready for use. FBS should last more than five years under these conditions. We do not recommend that FBS be defrosted and refrozen more than once.

We recommend rapid thawing: warm the frozen FBS at room temperature for 10 minutes, and then place into a 37°C water-batch. Rapid thawing limits high salt concentrations, which can potentially degrade serum proteins. Gently rotate-do not shake as this can cause detrimental foaming. FBS should be removed from the water batch when fully thawed, and not be allowed to warm to ambient temperature. When thawed, FBS is normally a clear amber solution; however, there may be small amounts of crystalline precipitates (salts, lipids, & proteins), which will not affect performance. Filtration of these precipitates is usually not necessary or recommended. Thawed FBS should be stored at 4°C and used with 2-3 weeks.

FBS is typically used at 1-20% (vol) for media preparation in tissue culture, with 10% (vol) being the most common.

As FBS is a complex animal product, there can be significant batch-to-batch variation. While we performance-test each batch on several common cell lines, we recommend that end-users batch test sera on their particular cell line(s); we provide free samples for testing and can reserve batch lots if so requested.