Accepted answer
Nobody has published a cycle count, and at 3.33 mg/mL the concentration tells you what a wrong guess costs: a 0.1 mL aliquot holds 0.33 mg and every microlitre is 3.33 µg. Damage from freezing is not gradual attrition — it is concentrated at the phase transitions, where ice excludes solute and the unfrozen fraction climbs well above 3.33 mg/mL for as long as the transition lasts. Two slow cycles can therefore do more than four fast ones, which is why a cycle count is the wrong unit in the first place. The way to make the number one is to make it one: split at reconstitution into single-draw aliquots, label each with 3.33 mg/mL and the date, and never thaw a container you will refreeze.
The relevant detail is that this is one of the few handling questions with a genuinely quantitative literature behind it.
Thaw slowly at room temperature or in the refrigerator rather than in warm water. Rapid warming creates local thermal and concentration gradients that promote aggregation.
Count cycles rather than worrying about degrees. Minus twenty and minus eighty differ far less than one cycle and five do.
Selective crystallisation of sodium phosphate buffer components producing large pH shifts on freezing is a classical result in the lyophilisation literature.
Count cycles, not degrees. The cycle is the damaging event.
7I have kept vials both ways for a year and this matches what I saw. – Dr_Sara_Kuusela 4 months ago 6Two lots stored differently, reassayed at a year — the difference was smaller than I expected. – Dr_Yusuf_Adeyemi 3 months ago add a comment