Are Hach Stablcal® Standard NIST certified?
Stablcal standards are not NIST ceritifed
The Formazin and Stablcal® solutions provided by Hach are not NIST traceable because NIST does not carry turbidity standards. However, Formazin and Stablcal® are accepted by the EPA as the primary standard to be used in the calibration of turbidity instruments. Hach Method 8195 is an EPA accepted method for measurement of turbidity and uses formazin solutions for instrument calibration. See the attached letter for more information.