The HI96770-03 are high quality reagents that are pre-measured, allowing for users to achieve fast and accurate colorimetric measurements. These reagents follow the USEPA Method 370.1 and Standard Method 4500-SiO₂ C in which the reaction between silica and reagents causes a yellow tint in the sample. By adding the powder packets in the appropriate order, the reaction will take place and Hanna’s compatible portable photometer (HI96770) will determine the concentration from the color that is produced. The results will be displayed in mg/L (ppm) of silica. These reagents are designed to be used with samples that have an expected range of 0 to 200 mg/L silica.