What are Izon calibrated particles and how should they be stored?

 Izon calibration particles (carboxylated polystyrene) are delivered in 0.5 mL vials that contain:

• Carboxylated polystyrene particles (size and concentration certified by Izon)
• Deionised water
• 0.05% sodium azide to prevent microbial growth

Calibration particles should be refrigerated when not in use. DO NOT FREEZE.