This Standard Reference Material (SRM) is intended primarily for use in the evaluation of techniques used in the analysis of coals and materials of a similar matrix. A unit of SRM 2685c consists of 50 g of bituminous coal ground to pass a 250 ?m (60 mesh) sieve, homogenized, and packaged in an amber glass bottle under an argon atmosphere, and sealed in an aluminized bag.

SRM 2692c Bituminous Coal (Nominal Mass Fraction 1 % Sulfur) - This Standard Reference Material (SRM) is intended primarily for use in the evaluation of techniques employed in the determination of sulfur, mercury, chlorine, and ash content in coal and materials of a similar matrix. A unit of SRM 2692c consists of 50 g of bituminous coal ground to pass a 250 µm (60 mesh) sieve, homogenized, and packaged in an amber glass bottle. This data is public in the Certificate of Analysis for this material.

Standard Reference Material 2693 Bituminous Coal (Nominal Mass Fraction 0.5 % Sulfur) - This Standard Reference Material (SRM) is intended primarily for use in the evaluation of techniques employed in the determination of sulfur, mercury, chlorine, and ash content in coal and materials of a similar matrix. A unit of SRM 2693 consists of 50 g of bituminous coal ground to pass a 250 µm (60 mesh) sieve, homogenized, and packaged in an amber glass bottle and then sealed in an aluminized bag. This data is public in the Certificate of Analysis for this material.

SRM 2973 Vitamin D Metabolites in Frozen Human Serum (High Level) - This Standard Reference Material (SRM) is intended for use as an accuracy control in the critical evaluation of methods for determining the amount-of-substance concentration of vitamin D metabolites in human serum. This SRM can also be used as a quality assurance tool for assigning values to in-house control materials for these constituents. This data is public in the Certificate of Analysis for this material.

This Standard Reference Material (SRM) is intended for use as a primary calibration standard for the quantitative determination of tungsten. A unit of SRM 3163 consists of 50 mL of an acidified aqueous solution prepared gravimetrically to contain a known mass fraction of tungsten in a high-density polyethylene bottle sealed in an aluminized bag.

SRM 2193a Calcium Carbonate pH Standard [used as saturated Ca(OH)2 solution] - This Standard Reference Material (SRM) is intended for use in preparing solutions for calibrating electrodes for pH measuring systems at pH values above 11.0. This lot of calcium carbonate (CaCO3) was selected for its low level of alkali metal impurities. However, this SRM is certified ONLY as a pH standard, NOT as a pure substance. A unit of SRM 2193a consists of 30 g of CaCO3. This data is public in the Certificate of Analysis for this material.

SRM 1946 Lake Superior Fish Tissue - This Standard Reference Material (SRM) is a frozen fish tissue homogenate that was prepared from lake trout (Salvelinus namaycush namaycush) collected near the Apostle Islands in Lake Superior (U.S./Canada), and is intended primarily for use in evaluating analytical methods for the determination of polychlorinated biphenyl (PCB) congeners, chlorinated pesticides, polybrominated diphenyl ether (PBDE) congeners, perfluorooctanesulfonic acid (PFOS), fatty acids (including omega-3 fatty acids), extractable fat, methylmercury, total mercury, proximates , ?-he

This Standard Reference Material (SRM) is intended for use as a primary calibration standard for the quantitative determination of mercury. A unit of SRM 3133 consists of five 10 mL sealed borosilicate glass ampoules of an acidified aqueous solution prepared gravimetrically to contain a known mass fraction of mercury. The solution contains nitric acid at an approximate mass fraction of 10 %. This data is public in the Certificate of Analysis for this material.

SRM 3669 Arsenic Species in Frozen Human Urine (Elevated Levels) - This Standard Reference Material (SRM) is intended primarily for validating analytical methods and measurements for the determination of arsenic species in human urine. A unit of SRM 3669 consists of five pouches each containing a vial of arsenic species in frozen human urine at elevated levels. Each vial contains nominally 1.5 mL of urine. This data is public in the Certificate of Analysis for this material.

SRM 2950a Respirable Alpha Quartz on Filter Media (Nominal Mass of Alpha Quartz: 5 µg to 500 µg) - This Standard Reference Material (SRM) is intended primarily for the calibration of X-ray diffraction (XRD) spectrometers for the determination of respirable alpha quartz using National Institute for Occupational Safety and Health (NIOSH) Method 7500, or the equivalent. This data is public in the Certificate of Analysis for this material.