What does sample contamination refer to?

Sample contamination specifically refers to the introduction of extraneous substances into a sample. This can happen at any stage of sample handling, from collection to analysis. When unwanted materials are added to the sample, they can interfere with the analysis, leading to inaccurate results. Contaminants may originate from the environment, equipment, or even the reagents used during the analysis.

In contrast, the other options describe different scenarios that do not align with the definition of sample contamination. Intentional addition of substances is more reminiscent of spiking samples for calibration, loss of analyte during testing pertains to analyte degradation or handling issues, and the use of outdated materials could affect the reliability of results but does not directly describe contamination. Therefore, the correct understanding of sample contamination is crucial for ensuring the integrity and accuracy of analytical measurements.