Besides temperature, what should also be controlled to preserve samples?

• A. pH
• B. Humidity
• C. Light exposure
• D. Volume

Answer: (A)

Maintaining a stable pH is essential for preserving many samples because chemical stability and biological activity are highly sensitive to acidity or basicity. Even with constant temperature, shifts in pH can accelerate hydrolysis, oxidation, and enzymatic degradation, altering the structure and function of proteins, nucleic acids, and other components. Using buffers keeps the pH within a narrow range, preventing these degradation pathways and helping preservation reagents work as intended. While humidity, light exposure, and sample volume can matter in certain contexts—moisture loss, photosensitive materials, or achieving consistent amounts—the pH environment directly governs the chemical stability of many samples, making it a critical control parameter.