blank environmental samples

Blanks for the field and lab, what are they?

blank environmental samplesBlanks are artificial samples (made up of ultra-pure MilliQ water) used to trace sources of contamination which may be introduced to samples:

  • During handling and transportation;
  • During sampling in the field (from contaminated equipment); and
  • During laboratory preparation and analysis.

Based on the potential contamination sources listed above, there are various blanks used to identify the contamination sources during the data-collection processes, if any.

Rinsate Blank: Otherwise known as an equipment blank, the rinsate blank is the analyte free water collected after it has been poured over or through contaminated field sampling equipment prior to the collection of environmental samples. This is to assess whether the decontamination process has been adequately undertaken and there is no residual contaminants from previous sampling.

Trip Blank: The trip blank is a clean sample of matrix that has been created in the laboratory to the sampling site and transported back to the laboratory without exposures related to sampling. The trip blank is typically analysed for volatile organic compounds which may have been introduced to samples during handling and transportation.

Field Blank: The field blank is analyte free water poured into a sampling container in the field and is carried with the field samples. This is to assess whether contamination may have occurred in the field during sampling.

Method Blank: The method blank is a sample that is representative of the matrix and is prepared and analysed through the same procedures as the field samples. This is used to assess contamination resulting from laboratory preparation and analytical procedures.

Blank Spike: The blank spike is similar to the method blank, a sample that is representative of the matrix is prepared with spiked concentrations of the analytes of interest and then prepared and analysed through the same procedures as the field samples. This is used to assess if the laboratory preparation and analytical procedures are being undertaken correctly.

Calibration Blank: The calibration blank is a clean sample of matrix that can be either used with prepared standards to calibrate instruments or used to verify the absence of contamination of instruments.

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