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Identifying Trip and Field Blanks

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Test tubesThe integrity of your samples is of the utmost importance to us at Eurofins Lancaster Laboratories Environmental. At ELLE, we have many checks and balances in place to ensure that the data we provided is high quality and legally defensible. In additional to these measures, the use of field blanks and trip blanks adds valuable background information when assessing the integrity of the data of the field samples. The blank data represents the environmental factors that could be present in the field samples, and under some methods the trip blanks and field blanks are required.

In this article, we will discuss the definition of a trip and field blank and when the blanks are required.

What is a Trip Blank?

A trip blank is typically used with samples collected for volatile organic compound (VOC) testing, and its purpose is to detect and identify any VOC contaminant of the samples from travelling to and from the lab. This blank represents the “trip” the volatile vials take from leaving ELLE with the bottle order to the field for sample collection and back to the lab for testing. The blank is created at the laboratory by completely filling the volatile vial container with lab grade deionized water and sealing the container. The trip blank vials are NOT to be opened until they’re about to be tested at ELLE. All ELLE trip blanks have a long sticker over the vial stating this.

Where do you store your volatile vials prior to a sampling event and where are samples stored prior to shipping to ELLE? Are they near vehicles, machinery, or gasoline? If so, there is a high probability the lab will detect VOCs that are present in gasoline in the samples and trip blank. The use and analysis of a trip blank will show what VOCs are coming from the trip the samples took verses what is present in the samples.

What is a Field Blank?

A field blank can be used with any type of analysis, and its purpose is to detect and identify any contaminant from the sampling site. Unlike trip blanks, field blanks are created in the field by the sampler. When you request a field blank from ELLE, you will receive bottleware for the requested analyses and lab grade deionized water to fill each bottle. The sampler opens the bottles in the field and collects the field blank by filling the bottles with the provided DI water. By doing this, the field blanks are exposed to the atmosphere of the sampling site. Like the trip blank, the field blank results can be used to identify the contaminants that are coming from the field.

A field reagent blank for PFAS by EPA 537 Rev 1.1 is slightly different than a field blank. Instead of pouring DI water into bottles containing the preservative, the DI water is mixed with the preservative at the lab and the preserved DI water is poured into an empty 250ml plastic bottle in the field.

Method Requirements

While blanks are always a good idea and add value to your project, there are several methods that require a blank to be analyzed if detections are found in the associated field samples. The table below summarizes this:

Method Name

Sample Type


Type of Blank Required

EPA 524.2: Measurement of Purgeable Organic Compounds in Water by Capillary Column GC/MS

Potable Water


Trip Blank

EPA 504.1: EDB, DBCP, and 1,2.3-TCP in water by Microextraction and GC

Potable Water

EDB, DBCP, and/or 1,2,3-TCP

Trip Blank

EPA 537 Rev. 1.1: Determination of Selected Perfluorinated Alkyl Acids in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS)

Potable Water


Field Reagent Blank

SW-846 Test Method 8011: EDB and DBCP in water by Microextraction and GC

Non-Potable Water

EDB, DBCP, and/or 1,2,3-TCP

Trip Blank

If the blanks listed above are not received at sample receipt, the lab will add a general comment to the report stating this.

Samples intended for PA Safe Drinking Water compliance require a trip blank to be used for compliance and monitoring purposes. If your sample arrives to the lab without the required trip blank, ELLE cannot report the data and monitoring violations may result.

We hope that you find this information useful. As we have stated previously, the integrity of your samples is of utmost importance to us. By adhering to these guidelines, you play an active role in this endeavor. Should you have any questions, please do not hesitate to contact your client services representative.