What is required for preserving samples for oil and grease analysis?

For preserving samples for oil and grease analysis, it is crucial to adjust the pH with hydrochloric or sulfuric acid. This step is necessary because many organic compounds present in oil and grease can be more effectively extracted and quantified at lower pH levels. Acidifying the sample helps to stabilize the constituents, preventing decomposition or other changes that might occur during storage.

Maintaining the right pH is vital to ensure the validity of the analytical results since certain reactions can alter the chemical properties of the oils and greases being measured. By adjusting the pH with these acids, it contributes to preserving the integrity of the sample until it can be analyzed.

Other methods, such as keeping the sample warm, using distilled water for dilution, or storing at room temperature, do not provide the same level of protection for the sample’s chemical characteristics and can lead to inaccurate results in the analysis of oil and grease.