HI747-11 is a high-quality set of calibration standards that allows users to validate the Copper Low Range Checker®HC - HI747. The HI747-11 includes one sealed cuvette for zero ppb copper and one cuvette that is tinted to an equivalent 500 ± 100 ppb copper sample @ 25oC. The calibration check set is produced in our state-of-the-art manufacturing facility using reagent grade chemicals in a temperature controlled environment.