Yes, we carry a high and low standard for each of our ISEs. These are used to calibrate the sensors. They come in 500 mL bottles.

Item Vernier Order Code
NH4 Low 1 mg/L as N NH4-LST
NH4 High 100 mg/L as N NH4-HST
NO3 Low 1 mg/L as N NO3-LST
NO3 High 100 mg/L as N NO3-HST
Ca Low 10 mg/L Ca CA-LST
Ca High 1000 mg/L Ca CA-HST
Cl Low 10 mg/L Cl CL-LST
Cl High 1000 mg/L Cl CL-HST