Rehydrated LAL reagent may be stored for as long as 24 hours, but it must be kept at 2-8 °C. Do not pre-incubate lysate in the LAL test tubes before adding samples to them. This is not necessary and may cause sensitivity loss in the LAL reagent. If you need to store rehydrated lysate for a longer period of up to four weeks, it must be kept frozen. Store it in a freezer below –10 °C. Make sure the lysate is actually frozen solid in the tubes! Many frost-free freezers have surface heating cycles which may periodically warm articles in contact with the heated surfaces. Repeated freezing and thawing of the lysate will result in deterioration well before four weeks have passed.