Total Dissolved Solids (TDS) is the measure of organic or inorganic substances dissolved in a certain liquid, and represents the proportion of the various solids. There are several uses for TDS: to show the level of purity of water, for example, and it can be used in agriculture. If you need to calculate the total dissolved solids in a certain liquid, go to step 1.
Steps
Step 1. Take a sample
Get a clean, sterilized beaker with no dust or other contamination. Fill the beaker with the liquid to be analyzed.
Step 2. Measure the conductivity of the liquid
You will need an electrical conductivity meter, an electronic instrument used for conductivity measurement. It works by releasing a current in the liquid and measuring the resistance exerted by that liquid. Turn it on and put the electrode in the shape of a tube or terminal in the water. Before writing the value, wait for the conductivity reading to be stable.
As an example, suppose we want to calculate the total dissolved solids in a water sample. After putting the electrical conductivity meter into the sample, you will have a value of 430 micro-Siemens / cm at 25 degrees Celso
Step 3. Enter the data in the formula for TDS
The basic formula for calculating total dissolved solids is like this: in the formula. EC is the conductivity of the sample and ke is the correlation factor. The correlation factor depends on the liquid used and can vary according to atmospheric conditions. You can find it for almost all liquids in the physics tables.
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In the example above, let's say the correlation factor to the current temperature and current pressure conditions is 0.67. Enter the values into the formula as follows. The TDS for the sample is therefore 288.1 mg / L.
Calculate Total Dissolved Solids Step 3Bullet1
Advice
- Water with a TDS of less than 1000 mg / L is considered clean.
- You can think of conductivity as practically the inverse of the electrical resistance exerted by a liquid on the flow of current.
- Siemens is a unit of measurement for conductivity. It is usually indicated by the letter S.
