This Standard Reference Material (SRM) is intended as a primary standard for the quantitative determination of nitrate using anion ion chromatography (IC) or other methods. A unit of SRM 3185 consists of five 10 mL sealed borosilicate glass ampoules of solution. The solution is prepared gravimetrically to contain a known mass fraction of nitrate dissolved in filtered (0.22 µm) water having a minimum resistivity of 18 megaohm centimeters. 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 phosphate using anion ion chromatography (IC) or other methods. A unit of SRM 3186 consists of five 10 mL sealed borosilicate glass ampoules of solution prepared gravimetrically to contain a known mass fraction of phosphate dissolved in filtered (0.22 ?m) water having a minimum resistivity of 18 megaohm centimeters. 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.

Standard Reference Material 3949 Folate Vitamers in Frozen Human Serum

SRM 635a Portland Cement (Blended with Slag) - This Standard Reference Material (SRM) is intended primarily for use in validation of chemical and instrumental methods of analysis of cements and materials of similar matrix for elemental contents. It can be used to validate value assignment of in-house reference materials. This data is public in the Certificate of Analysis for this material.

SRM 671 Nickel Oxide, No. 1 - Standard Reference Material 671, Nickel Oxide No. 1 has been discontinued and is no longer being produced. The data is public in the Certificate of Analysis for this material.

Standard Reference Material 672 Nickel Oxide, No. 2 has been discontinued and is no longer being produced. The data is public in the Certificate of Analysis for this material.

Standard Reference Material 673 Nickel Oxide, No. 3 has been discontinued and is no longer being produced. The data is public in the Certificate of Analysis for this material.

SRM 690 Iron Ore (Canada) is for use in checking chemical methods of analysis and in calibration with instrumental methods of analysis. This data is public in the Certificate of Analysis for this material.

SRM 691 Iron Oxide, Reduced is intended primarily for use in evaluating chemical methods and in calibrations associated with optical emission and x-ray spectrometric methods of analysis. This data is public in the Certificate of Analysis for this material.