Trip Blank - a sample of analyte free media supplied by the analyzing laboratory taken to the site and returned to the laboratory unopened.
The trip blanks and field blanks are prepared by the laboratory prior to a sampling event. If prepared in the analyzing laboratory, the water is checked daily to ensure that no contaminants are present in the water. If prepared by a non-laboratory location (depot), a duplicate of the blank is prepared by the technician to retain in the event contamination is questioned.
Frequency and Purpose
- The CCME recommends having 1 per water or soil submission with VOCs. Trip blanks for other analytes may be prepared if requested.
- Identifies any potential cross-contamination that may occur from other samples, ambient conditions, or other sources to which the samples may be exposed.
Application and Regulatory Criteria
- Evaluates the impact on data for results >2x the RDL or that which approaches the concentration reported in the sample.
Recommended Actions for Positive Results on Trip Blanks
- Escalate to your Customer Solutions Representative immediately.
- The laboratory may choose to:
- Retest the trip blanks
- Compare to other samples submitted
- Analyze any stored water
- Compare to analysis certificates of the blanks
- If unable to identify a source of laboratory contamination, your Customer Solutions Representative may be able to discuss where a field contamination source may have come from.