Blank

Blank - A sample subjected to the usual analytical or measurement process to establish a zero baseline or background value. Sometimes used to adjust or correct routine analytical results. A sample that is intended to contain none of the analytes of interest. A blank is used to detect contamination during sample handling preparation and/or analysis. There are many types of blanks, each with a specific purpose including:

   Equipment Blanks - Monitor for potential contamination from decontamination procedures of field gear or from other sources of equipment contamination like oil or other lubricants.
   Field Blank - A blank used to provide information about contaminants that may be introduced during sample collection, storage, and transport. A clean sample, carried to the sampling site, exposed to sampling conditions, returned to the laboratory, and treated as an environmental sample.
   Laboratory Blanks - Samples that are used to identify potential sources of contamination that are generated during the processing and analysis of samples in the laboratory.
   Method Blank - A blank prepared to represent the sample matrix as closely as possible and analyzed exactly like the calibration standards, samples, and quality control (QC) samples. Results of method blanks provide an estimate of the within-batch variability of the blank response and an indication of bias introduced by the analytical procedure.
   Trip Blank - A clean sample of a matrix that is taken to the sampling site and transported to the laboratory for analysis without having been exposed to sampling procedures.

[Category=Quality Assurance ]

Source: Massachusetts Department of Environmental Protection, 16 March 2011 09:34:19, http://www.mass.gov/dep/cleanup/laws/glossa01.htm