Place the ammeter plates into the sample and run a sine wave voltage through them. Note the voltage you ran through them and measure the current in amperes.
Divide the amperes by the voltage to get conductivity. The unit of conductivity is Siemens per centimeter.
Adjust conductivity if your liquid is susceptible to change with variance in temperature, as with water or some alcohols. Multiply your answer from Step 2 by (1 + constant(T-Tcal)). Here, T is the temperature now, the constant is the temperature coefficient at a particular temperature, and Tcal is the temperature at which that temperature was calibrated. For example, KCl (potassium chloride) has a constant of 1.88 at 25 degrees Celsius.
Measure the TDS of the water using your TDS meter. Divide this value by the answer from Step 3 to get the TDS factor for your sample.