Water Analysis: Total Dissolved Solids (TDS)
Measures of the nutrient material dissolved in the water are indicators of productivity. High total suspended solids usually indicate fertile and producing waters. The experiment testing for the Total Dissolved Solids (TDS) is rather simple, but requires exact measurements. Using an analytical balance that weighs to the 0.0001 g is desirable.
Weight to the nearest 0.0001 g, if possible, 3 clean dry 250 ml beakers or evaporating dishes. Pour 100.0 ml of the filtrate from the TSS experiment (See Total Suspended Solids) in each of the containers. Slowly and carefully evaporate the water sample to dryness, using a hot plate. Do not let the samples get too hot or some of the dissolved solids may be vaporized or decomposed.
When the samples are dry, reweigh the containers and determine the weight of the solids dissolved in 100 ml of water. Average the 3 values. Convert the result to ppm by multiplying the value obtained by 10,000.