What is the purpose of a field blank when collecting samples?

The purpose of a field blank when collecting samples is to validate the field sample's integrity. A field blank is essentially an uncontaminated sample that is taken through the same sampling process as the actual samples but contains no analytes. This helps in identifying any potential contamination that could occur during collection, transport, or analysis. By analyzing the field blank, one can determine whether any chemicals or contaminants were introduced from the sampling equipment or environment, thus confirming the reliability of the field samples.

This ensures that any results from the actual samples reflect the true concentrations of the substances of interest without interference or false positives from external sources. Therefore, a field blank is critical for maintaining the integrity and validity of the sample data.