Quality Control

 The Trace Element Analysis Laboratory follows quality control procedures outlines in EPA SW 846 (http://www.epa.gov/osw/hazard/testmethods/sw846/online/index.htm) and EPA method 6020 (http://www.epa.gov/osw/hazard/testmethods/sw846/pdfs/6020a.pdf) . These procedures are outlined below.

Calibration: The ICP-MS is calibrated using NIST traceable single and multi-element standards containing the analytes of interest. Multi-point calibration curves (n ≥ 5) are constructed for each analyte with correlation coefficient criteria > 0.995. The calibration is followed by an Initial Calibration Blank (IBC) and an Initial Calibration Verification (ICV). The ICV (which is also the solution for subsequent Continuing Calibration Verifications (CCV)) is made from a second source of single and multi-element standards and contains all the analytes at concentrations at or below the mid-point calibration range. Acceptance criteria for the ICV and CCV are ± 10%. The CCV is run after every 10 samples.

Laboratory Control Samples (LCS) and Standard Reference material (SRM): The TEA generally uses Standard Reference Materials (SRM) as LCS’s. For solid samples the SRM is chosen to match the sample matrix (soil/sediment/animal tissue/plant tissue) as closely as possible. The LCS is taken through all sample preparation steps and handled in an equivalent manner to a sample. For aqueous samples the LCS is a Certified Water Sample such as SLRS 6 or similar. Acceptance criteria for LCS are ± 20% of the certified or accepted value.

Duplicates and Spikes: Unless sample is limiting, duplicate and spike analysis are performed on all sample batches. Duplicate solid samples are digested at a frequency of one duplicate per 20 samples. Analytical duplicates and spikes are performed at a frequency of one each per 20 samples. Recovery criteria for all analytes are 80%-120% of the spike amount.

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