Polystyrene samples mounted on a standard wheel must be replaced after five years from the date of issue.
Because card-mounted standards are handled regularly and, therefore, exposed to potential contamination, damage and degradation, they must be replaced after two years from the date of issue.
The 1.5 mil polystyrene is traceable to NIST SRM 1921a, and the NG11 glass is traceable to NPL Schott NG11. Analysis methods are based on ASTM E 1421-99 (2004) Standard Practice for Describing and Measuring Performance of Fourier Transform Mid-Infrared (FT-MIR) Spectrometers: Level Zero and Level One Tests.