Tech Tips

Salinity Kit- What's the endpoint?

Question: I use the LaMotte Salinity Kit (7459-01) with my students to test the waters at a local estuary. I like the titration, but the kids always have a heated discussion about the endpoint. Do you have a color chart to use with this kit?

Answer: In the salinity titration, salinity indicator A turns the water a clear yellow color. The intensity will vary a little based on the sample. As salinity indicator B is added, the sample changes to a milky yellow color and finally to a milky pink-brown color. The titration endpoint is at the first sign of a pink color. Our lab tech describes this color as tomato soup with milk in it. This description accurately describes both the color and texture of the endpoint. There is no color chart because this color on laminated print material is hard to recreate.