Several methods and apparatuses for determining whether a vaccine specimen has previously frozen. One method includes providing a known value correlating to the settling of vaccine known to have previously frozen, and, upon agitation of the specimen, directing light substantially through the specimen as the specimen settles. The amount of light that passes through the specimen correlates to the settling of the specimen and is compared to the known value to determine whether the specimen has previously frozen. Another method includes providing light of a predetermined wavelength and directing the light through the specimen. The intensity of the light transmitted through the specimen is compared to the intensity of light of the predetermined wavelength having passed through an amount of vaccine known to have previously frozen. Based on this comparison, a determination is made whether the specimen has previously frozen.
