HI-747-25 Copper LR Checker reagents The HI-747-25 are high quality reagents that are pre-measured, allowing for users to achieve fast and accurate measurements with their Copper Low Range Checker® HC. These reagents follow the Bicinchoninate Method in which the reaction between copper and the reagent causes a purple tint in the sample. By simply adding the packet of HI-747-25 reagent to the sample, the reaction will take place and the HI-747 will determine the concentration from the colour that is produced. The results will be displayed in ppb of copper. These reagents are designed to be used with samples that have an expected range of 0 to 999 ppb copper.