Sunday, 15 May 2016

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 180OC. 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 103OC to 105OC 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 105OC 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)

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