Which storage practice is essential to protect temperature-sensitive reagents from light and minimize freeze-thaw cycles?

• A. Store in a well-lit room at room temperature.
• B. Store refrigerated or frozen as specified; protect from light with opaque containers or foil; minimize freeze-thaw cycles and monitor storage conditions.
• C. Store in direct sunlight.
• D. Store in a humid cabinet.

Answer: (B)

Temperature-sensitive reagents need controlled storage that addresses both light exposure and temperature stability, plus minimal freeze-thaw events. Store refrigerated or frozen as specified, protect from light with opaque containers or foil, and minimize freeze-thaw cycles by aliquoting and monitoring storage conditions. Light can drive photochemical degradation, altering the reagent’s activity, while repeated freezing and thawing can cause denaturation, precipitation, or loss of potency. The other options fail because they expose reagents to heat and light or neglect light protection and temperature control, leading to faster degradation or instability.