What is the purpose of field blanks versus trip blanks in sample handling?

• A. Field blanks check contamination at the sampling site; trip blanks verify contamination during transport from the field to the lab.
• B. Field blanks check calibration; trip blanks measure humidity.
• C. Field blanks calibrate instruments; trip blanks calibrate at lab.
• D. Field blanks measure temperature; trip blanks measure pressure.

Answer: (A)

The main idea is QA/QC in sample handling: blanks are used to detect where contamination might be entering the process. A field blank is treated like a real sample but is kept in the field environment without exposing it to the actual ambient air being sampled. By handling and opening it in the field the same way as the real samples, any contaminants that appear in the field blank point to contamination from field handling, equipment, or site conditions.

A trip blank, on the other hand, is prepared and sent from the lab to the field and back. It experiences the same transport, handling, and storage conditions as the actual samples, so any contaminants found in the trip blank indicate contamination introduced during transport or during field handling on the way to the lab.

Together, these blanks help determine whether detected contaminants come from the sampling site itself or from the transport and handling process, ensuring the data reflects true ambient conditions rather than artifacts of the workflow.