A Certified Spiking Solution® of (±)-Metanephrine HCl and (±)-Normetanephrine HCl. This multi-component mix is suitable for critical quantitative applications in research and clinical environments including: for use in preparation of controls, calibrators, and linearity standards for LC-MS/MS assays; as system tuning/suitability standards; linearity verification; and internal proficiency testing. The stable, quantitative solution format provides significant benefits to the user such as convenience of use, material savings, and increased efficiency of labor.