Water Analysis : Estimation of Total Dissolved Solids(TDS)

PRINCIPLE:

A well mixed sample is filtered through a standard glass filter and the filtrate is evaporated to dryness in a weighed dish and dried constant weight at 180^OC. The increase in the dish weight represents the total dissolved solids.

REQUIREMENT:

·         Evaporating dishes (100 ml capacity)

·         Oven

·         Weighing balance

·         Beakers

·         Measuring cylinders

PROCEDURE:

·         Heat clean dish to 103^OC to 105^OC for 1 hour. Store and cool dish in desiccators until needed. Weigh immediately before use.

·         Shake the water sample very well and add 100 ml into filtration device that is having glass filter on it. Apply vacuum and filter out 100 ml of sample.

·         Collect the filtrate, in to evaporating dish.

·          Put the dish into an oven at 105^OC for overnight.

·         Next day take out it from the oven and cool in tin desiccators dish would be having dried residues in it.

·         Measure the weight of evaporating dish.

·         Put the data or the pre weight and post weight of the dish in the following equation and calculate the amount of total solids present in the sample.

Calculation:

mg total solids/L =  (A-B) x1000

  mL of sample

Where, A = post weight of dish (weight of dried residues + dish)

B= pre weight (weight of dish, mg)