Some frozen solutions may deteriorate if thawed and left unfrozen for any length of time. A solution that has thawed needs to be evaluated for potency and safety before it can be used. Certain techniques can be used to detect if a frozen solution has thawed.


A solution may be frozen in:

(1) a solid (glass, plastic) container (tube, bottle)

(2) a flexible plastic bag


Frozen Solution in a Bottle or Tube

What You See if Solution Thaws

freeze at a slant (45 degrees) and store vertical

horizontal surface

freeze on side with sterile glass beads

glass beads will be in bottom of container



• If frozen at an angle mark the surface of the fluid with a marking pen.


Frozen Solution in a Flexible Bag

What You See if Solution Thaws

indent with tube or band while freezing

indent disappears

freeze on side with a few bubbles, and store vertical

bubbles will no longer be on the side


There are other ways to detect thawing:

(1) monitored refrigerator with data storage

(2) thermometer that records a maximum temperature


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