Store at room temperature. Adequate ventilation. Protect from heat. Protect from light.

Simultaneous determination of 12 steroids by isotope dilution liquid chromatography-photospray ionization tandem mass spectrometry: Tiedong Guo^a, Robert L. Taylor^e, Ravinder J. Singh^e and Steven J. Soldin^{a, b, c, d,}; Author Affliations: ^aBioanalytical Core Laboratory, General Clinical Research Center, Georgetown University, Washington, DC, USA; ^bDepartment of Medicine, Georgetown University, Washington, DC, USA ^cDepartment of Pharmacology, Georgetown University, Washington, DC, USA; ^dDepartment of Laboratory Medicine, Children's National Medical Center and Department of Pediatrics and Pathology, The George Washington University School of Medicine, Washington, DC, USA^eDepartment of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA