Total solids are measured by weighing the amount of solids present in a known volume of sample. This is done by weighing a beaker, filling it with a known volume, evaporating the water in an oven and completely drying the residue, and then weighing the beaker with the residue. The total solids concentration is equal to the difference between the weight of the beaker with the residue and the weight of the beaker without it. Since the residue is so light in weight, the lab will need a balance that is sensitive to weights in the range of 0.0001 gram. The technique requires that the beakers be kept in a desiccator, which is a sealed glass container that contains material that absorbs moisture and ensures that the weighing is not biased by water condensing on the beaker.
Some desiccants change color to indicate moisture content.
The measurement of total solids cannot be done in the field. TASK 2 Prepare before leaving for the sampling site Refer to section 2.3 - Safety Considerations for details on confirming sampling information. Be sure to let someone know where you are going and when you expect to return. Samples that are sent to a lab for total solids analysis must be tested within seven days of collection. Keep the samples on ice or refrigerated.