Samples taken for routine analysis should be preserved by?

• A. Refrigeration
• B. Freezing
• C. Drying
• D. Heating

Answer: (A)

Preserving samples for routine analysis aims to slow down biological activity and chemical changes so the sample remains representative until analysis. Refrigeration at about 1–4°C reduces microbial growth and slows most chemical reactions, keeping the concentrations of dissolved constituents close to their original values during the typical holding time.

Freezing can cause changes when thawed and may affect volatile components or the sample matrix. Drying removes water, concentrating solutes and altering the sample composition. Heating accelerates reactions and can degrade or volatilize analytes. For these reasons, refrigeration is the preferred preservation method for routine analyses.