The Freeze Drying Indicator is a mannitol/lyoprotectant solution (Lyophilization Reagent 2X Concentrate) with an added colorimetric indicator. It is a pink solution that turns blue upon lyophilization, thus providing a real-time, visual measurement of dryness. When using this reagent, complete removal of water yields a blue cake, while incomplete removal of water is illustrated as pink streaks or a pink crust.
OPS Diagnostics’ Freeze Drying Indicator is filter sterilized and is packaged aseptically in 500 ml PET bottles. Like Lyophilization Reagent (2X) Concentrate, it can be used at full strength or diluted 1:1 with samples prior to freeze drying. Lyophilized control solutions that are pink contain >2% moisture, while solutions that are blue with residual pink color are <2% moisture. Samples that are only blue are completely dry. It is useful in optimizing freeze drying runs in that it is an indicator of sample dryness during both the primary and secondary drying steps.