What type of samples require refrigeration for proper preservation?

Certain samples, particularly chemical and biological ones, require refrigeration to maintain their integrity and accuracy before analysis. Refrigeration slows down the growth of microorganisms and the degradation of chemical substances that could otherwise alter the sample composition.

Biological samples are particularly sensitive; they may contain living organisms whose activity can change the sample’s characteristics at room temperature. Additionally, many chemical samples might undergo reactions or degradation at higher temperatures. Therefore, refrigeration is critical to preserve the samples in their original state until they can be properly analyzed.

This need for refrigeration applies broadly across various types of samples, distinguishing the correct answer as one that encompasses both chemical and biological categories rather than limiting it to only one type or specific cases like alkalinity.