Which sample type commonly requires dark storage and cold temperatures to preserve viability?

• A. Microorganism samples
• B. Dissolved ion samples
• C. Fluoride samples
• D. VOC samples

Answer: (A)

Preserving viability means keeping living organisms alive for culture or viability-based analyses. To do that, samples are stored in darkness and cold to minimize light-driven damage and slow metabolic activity. Light can cause photodamage to cells and DNA, and heat accelerates deterioration or overgrowth; chilling reduces metabolic rate and helps maintain the microbial population until the lab can process it. Therefore microorganism samples commonly require dark storage and cold temperatures. Other sample types involve inorganic ions or chemicals that are not living; their stability isn't about keeping organisms alive, so they don't rely on darkness for viability, though some may still be refrigerated to slow changes or losses in concentration.