Why do so many of the QC operations (MS, MSD, LCS, blanks, etc.) have to be run “once for every 20 samples?
The 1 per 20 (5%) frequency is a default value that has been used in many EPA programs for many years. EPA also recognizes that other frequencies may be appropriate under other circumstances. For example, in the case of a long-term monitoring project involving a small number of analyses of a sample matrix that does not change, it should not be necessary to prove that the method applies to the matrix each time that samples are collected and analyzed. Therefore, the MS/MSD analyses could be run less frequently than 1 every 20 samples. To that end, EPA recommends that, if another frequency for the QC analyses is chosen, it be clearly documented in a sampling and analysis plan that is reviewed and approved by the relevant regulatory authority.
Related Questions
- Where do I specify the Laboratory Quality Control (QC) sample type (i.e., Matrix Spike/Matrix Spike Duplicate (MS/MSD)?
- Why do so many of the QC operations (MS, MSD, LCS, blanks, etc.) have to be run "once for every 20 samples?
- What if when I run Ferret32, the top line and Controls are hidden under my MS OFFICE ToolBar?
