Total Dissolved Solids (TDS)
How does OLI rigorously calculate TDS?
OLI originally developed the TDS calculation according to parameters set forth in ASTM D5907-03 (American Society of Testing Methods, West Conshocken, PA, United States). Recently this technique was modified to follow the parameters in ASTM D5907-18.
Both techniques heat a 1.0 L of solution of liquid to 180 oC which should remove all the volatile components. The mass remaining is the TDS in mg/L
Occasionally this calculation will fail, especially with solutions that are dilute. In such cases an estimated TDS value is returned which is the sum of all liquid species minus water.