Pre-extraction Standard

{
  "id": "MLC-T-ENV-021920",
  "term": "Pre-extraction Standard",
  "field": "Environment",
  "definition": "A group of isotopically labeled compounds added in a known amount to the XAD-2 adsorbent resin of each sample immediately before extraction and used for quantitation of target and other labeled compounds to correct for extraction, cleanup, and concentration recovery. These isotopically labeled compounds constitute a matrix spike of the resin. Add pre-extraction standard to every sample at the same level (including blank, QC samples, and calibration solutions).",
  "references": [
    "40 CFR 63.11426 (2023)"
  ],
  "url": "https://mlchart.com/terminology/environment/pre-extraction-standard/"
}