Sample refrigerators should be set at what temperature, plus or minus 2 degrees C?

Sample refrigerators should be set at what temperature, plus or minus 2 degrees C?

• A. 4C
• B. -20C
• C. 20C
• D. 0C

Answer: (A)

Maintaining sample integrity by refrigerating at about 4°C. Refrigeration at 4°C slows biological activity and chemical changes that could alter samples before analysis, and the allowed deviation is ±2°C, so the temperature should stay roughly between 2°C and 6°C. Four degrees sits squarely in that range and is a standard setting for preserving wastewater samples. Other temps are unsuitable: -20°C is a freezer setting that could freeze samples and alter constituents; 20°C is room temperature and allows rapid changes; 0°C is near freezing and may not be reliably within the required range.

Maintaining sample integrity by refrigerating at about 4°C. Refrigeration at 4°C slows biological activity and chemical changes that could alter samples before analysis, and the allowed deviation is ±2°C, so the temperature should stay roughly between 2°C and 6°C. Four degrees sits squarely in that range and is a standard setting for preserving wastewater samples. Other temps are unsuitable: -20°C is a freezer setting that could freeze samples and alter constituents; 20°C is room temperature and allows rapid changes; 0°C is near freezing and may not be reliably within the required range.