Total Solids Presentation

By

Douglas Rittmann, Ph.D., P.E.Water/Wastewater Consultant

Presented to

UTEP Lab Class

On

February 28, 2006

Total SolidsTotal Solids

1. General Discussion

a. A well mixed sample is evaporated in a weighed dish and dried to constant weight in an oven at 103O to 105O C.

b. Interferences – Hygroscopic minerals require prolonged drying & rapid drying. Disperse oil and grease and floating material.

2. Apparatus

a. Evaporating Dishes – 100 ml capacity

1. Porcelain, 90 mm diameter

2. Platinum dishes – generally satisfactory for all purposes

Total Solids

3. High Silica Glass

b. Muffle Furnace for operation at 550OC

c. Steam Bath

d. Dessicator – dessicant with color indicator

e. Drying oven for operation at 103 – 105 degrees C.

f. Analytical Balance capable of weighing to 0.1mg

g. Wide Bore Pipets

Total Solids

3. Procedure

a. If volatile solids to be determined, ignite dish at 550OC for1 hour or if only total solids to be determined, heat dish at 103-105OC for 1 hr. Store and cool dish in dessicatoruntil needed. Weigh before use.

b. Sample analysis: *Choose sample volume = residue between 2.5 & 200 mg.

*Stir sample volume with magnetic stirrer.*Pipet sample volume from center of container*Dry sample at 103-105 degrees C. for at least 1 hour*Cool dish in dessicator and weigh after constant weight is obtained*Be alert to weight change due to air exposure.*Analyze at least 10% of samples in duplicate.*Duplicate samples should agree within 5% of average weight.

Total Solids

4. Calculation

Mg total solids, L = (A – B) X 1000 sample volume, ml

Where A = weight of dried residue + dish, mg, andB = weight of dish, mg.

5. Precision

Single laboratory duplicate analyses of 41 samples of Water and Wastewater samples were made with a standarddeviation of differences of 6.0 mg/L

Questions?