Comments on Certificates of Analysis (data reports) are meant to acknowledge situations when sample data falls outside recommended control limits or when the laboratory modifies standard procedures to accommodate the sample and analysis. It provides a narrative of anything important or significant that occurred during the analysis process that the data reviewer should be aware of.
Such comments may indicate that the detection limit was modified as a cause of target compound concentration, elevated moisture or insufficient sample volume. Other situations may include notes that a sample was analyzed past regulation hold time.
Observations made upon sample reception, such as temperature of samples, broken missing containers, presence or absence of the custody seal, wrong type of container or preservative or presence of sediment, may also be included.
A comment may also be present to indicate and explain the reason for which a quality control parameter falls outside control limits, or the interpretation of data points.