HI-747-11 is a high-quality set of calibration standards that allows users to validate the Copper Low Range Checker®HC – HI-747. The HI-747-11 includes one sealed cuvette for zero ppb copper and one cuvette that is tinted to an equivalent 500 ± 100 ppb copper sample @ 25°C. The calibration check set is produced using reagent grade chemicals in a temperature controlled environment.