Sample Collection: Certified Reference Standards


Certified Reference Standards (CRS)

CRS tubes are recommended in many key standard methods (e.g. US EPA Method TO-17) for auditing purposes and as a means of establishing analytical quality control.


Markes International CRS tubes are certified traceable to primary standards, have a minimum 6 month shelf life and are available with concentrations varying from 10 ng to 100 µg per component.  Each pack of CRS tubes includes a shipping blank to demonstrate the integrity of the storage and transportation process.  Chromatograms from this shipping blank, and an example analysis of a CRS tube are supplied along with the CRS Certificate.

CRS tubes are available loaded with:


  • Benzene, toluene and xylene at levels of 25 ng or 1 µg per component .
  • TO-17 standard at 25 ng per component of benzene, toluene, xylene, dichloromethane, 1,1,1-trichloroethane, 1,2,4-trimethylbenzene, methyl-t-butyl ether, butanol, ethyl acetate, methylethyl ketone).

Custom CRS tubes are also available on a variety of sorbents for a wide range of compounds