OBJECTIVE
To determine the Total Dissolve Solids in the given water samples.

PRINCIPLE
Basic principle involved is gravimetric. A well mixed sample is filtered through standard glass fibre filter and the filtrate is evaporated to dryness in an oven at 103 - 105◦C. The increase in weight represents the TDS.
The term residue denotes the material remaining in the dish after evaporation of water sample and drying in an oven at a definite temperature.

INTERFERENCE:
Highly mineralized water with considerable calcium, magnesium, chloride and/or sulphate content may be hygroscopic and require prolonged drying, proper dessication and rapid weighing.

PROCEDURE:
1) Dry the well cleaned dish in an oven at 103 – 105 ◦C for 1 hr
2) Cool, dessicate and take the initial weight of the dish
3) Repeat the above test (2) until a constant weight is obtained
4) Transfer a known volume of filtered homogenous sample into the dish.
5) Evaporate to dryness on a steam bath
6) Dry the evaporated sample in an oven at 103 – 105 ◦C for 1hr
7) Cool in dessicator and weigh

FORMULA USED

TDS (mg/ltr) = {(A-B) x 10^6}/V

Where, A = weight of dish residue in mg
B = weight of dish in mg
V = volume of sample in ml

OBSERVATIONS

V= 25 ml

Sample No. A B
1. 47.7494 47.7165
2. 48.6725 43.9419
3. 44.8594 44.8357
4. 52.7158 52.6922







RESULTS
Sample No. TDS (mg/l)
1. 1316
2. 1324
3. 948
4. 944

The results show that the TDS in groundwater samples is greater than that of the polluted samples.

By-Riddhi singh