text: NRC produces certified reference materials of biological tissues, isotopic standards, natural waters, sediments, supplements, and natural health products. With the exception of the ORMS, the river water CRM with elevated mercury, all materials contain natural levels of analytes in their native matrix.
  * Biological tissues
  ** DOLT, dogfish liver for trace metals
  ** DORM, fish protein for trace metals
  ** LUTS, non-defatted lobster hepatopancreas for trace metals
  ** TORT, lobster hepatopancreas for trace metals
  * Isotopic materials
  ** NIMS, natural inorganic mercury standard
  ** EMMS, isotopic methylmercury standard
  * Natural waters
  ** CASS, near-shore seawater for trace metals 
  ** MOOS, seawater for nutrients
  ** NASS, seawater for trace metals 
  ** ORMS, river water for mercury
  ** SLEW, estuarine water for trace metals
  ** SLRS, river water for trace metals
  * Sediments
  ** HISS and MESS, marine sediment for trace metals and major constituents 
  ** PACS and SOPH, marine sediment for trace metals and major constituents
  * Supplements and natural health products
  ** CACB, calcium carbonate for lead and cadmium
  ** FEBS, otolith for trace metals
  ** SELM, selenium-enriched yeast for selenium