The HI93706-03 are high quality reagents that are pre-measured, allowing for users to achieve fast and accurate colorimetric measurements. The method is an adaptation of the Standard Methods for the Examination of Water and Wastewater, 18th edition, Amino Acid method. The reaction between phosphate and reagents causes a blue tint in the sample. By simply adding the reagents to the sample, a reaction will take place and a compatible benchtop or portable meter can be used to determine the concentration from the color that is produced. The results will be displayed in mg/L (ppm) of phosphorus (P). These reagents are designed to be used with samples that have an expected range of of 0.0 to 15.0 mg/L phosphorus.

These reagents do not measure reactive, acid hydrolyzable or total phosphorous. Separate reagents must be ordered to measure these forms of phosphorous with the appropriate meter. The HI93706-0 reagents are measuring ortho phosphate and reporting only the phosphorous portion.