The solid secondary standard is a great tool for tracking instrument performance after calibration with a liquid primary standard. On a periodic basis, before making measurements with the instrument, use the solid secondary standard to verify the calibration. If the solid secondary standard value has changed by more than ± 5% of its assigned value, the instrument should be recalibrated.
The solid secondary standard can also be used to set the instrument for in vivo applications. After calibration of the instrument with a liquid standard, adjust the solid secondary standard to match the readings displayed with the liquid standard or a known concentration of desired algal sample. Please refer to the below Technical Note on how to use a solid standard. A solid secondary standard contains a stable fluorescent material that is intended to give you consistent repeatable readings.