Total Solids Presentation By Douglas Rittmann, Ph.D., P.E. Water/Wastewater Consultant Presented to UTEP Lab Class On February 28, 2006

Total Solids 1. General Discussion A well mixed sample is evaporated in a weighed dish and dried to constant weight in an oven at 103O to 105O C. Interferences – Hygroscopic minerals require prolonged drying & rapid drying. Disperse oil and grease and floating material.

Total Solids 2. Apparatus a. Evaporating Dishes – 100 ml capacity 1. Porcelain, 90 mm diameter 2. Platinum dishes – generally satisfactory for all purposes 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 If volatile solids to be determined, ignite dish at 550OC for 1 hour or if only total solids to be determined, heat dish at 103-105OC for 1 hr. Store and cool dish in dessicator until needed. Weigh before use. 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, and B = weight of dish, mg. 5. Precision Single laboratory duplicate analyses of 41 samples of Water and Wastewater samples were made with a standard deviation of differences of 6.0 mg/L

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