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Conductivity (TDS)

Conductivity of electricity (EC) in a liquid and water shows differences dependent on the chemicals and substances found in the solution, where solids, salts, and contaminants, increase the EC value, while pure and drinking water has a lower EC value.

The EC value is measured in microSiemens (µS/cm) and readings generally fall between 30 µS/cm to 2000 µS/cm, for water of high quality while ocean water and brine will have a reading of approximately 40,000 µS/cm and greater.  Higher values also signal pollution and contamination and are used routinely in the field to test for water potability. 

Substances that are dissolved in liquids (called Total Dissolved Solids, TDS) can be salts, minerals inorganic metals and compounds present that signals  impure water, and is measured in parts per million (PPM) and in milligrams/liter.   Good quality water has values between 0 and 600 ppm and values over 1200 ppm are considered an unsatisfactory level of TDS.  By measuring the microSiemens (µS/cm) of a water sample its an easy conversion of EC to the TDS value, and the two values are readily interconverted.

At CP Lab Chemicals we provide the solvents, reagents, and Chemical Standards of Conductivity for accurate, reliable and reproducible generation of the EC values by conductimetric measurements using portable or laboratory instruments and for the determination of Total Dissolved Solids.

Laboratory chemicals:  Conductivity standards are made from various salts or other ionizable chemicals, such as sodium chloride or potassium chloride being the ones most frequently used.

Practical Uses of Conductivity Measurements

Hard water measurement and mediation of hard water in industrial processes (scale buildup), including laundries, swimming pools and cooling and circulation systems. Hydroponics, aquaculture and agriculture all measure conductivity and EC values as plants and animals  respond to TDS concentrations differently, and higher economic return and productivity in agriculture are achieved by  changing pH and TDS levels in each growing habitat.

Conductivity Standards and Products Catalog Quick List

Analytical Products and Chemicals Catalog Quick List

 Conductivity Methods: 

  1. EPA Methods for Conductivity Measurement Method 120.1: Conductance (Specific Conductance, µmhos 25°C) by Conductivity Meter