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Department of Health Services— TiNe 22 ToWrity Screen Test 4 WASTE SAMPLE PREPARATION Dry Waste Material Each sample is identified as a Type i, Type ii or Type iil material.The samples are weighed into pre-tared Erlenmeyer flasks to yield final replicate sample concentrations of 250 mg/i, 500 mg/I, and 750 mg/I.Approximately 200 ml of dilution water is added to each flask. The flasks are capped with parafilm, a neoprgne stopper and aluminum foil and are mechanically shaken for six hours. d Liquid Waste of Low Viscosity To determine the volume of a low viscosity liquid sample needed to dose the toxicity test, the specific gravity is measured. The waste sample to be used in the toxicity test is first mechanically shaken or homogenized so asap evenly distribute any particulate matter in the sample. A known amount of sample, usually 20 ml, is drawn up through a volumetric pipette and dispensed into a 100 ml beaker that has previously been weighed on a Mettler balance to four decimal places. The beaker containing the known volume of sample is then re-weighed-on the Mettler balance.The difference In weight of the beaker with the sample and the weight of the beaker when it is empty is divided by the known volume of the sample On milliliters) to determine the specific gravity. This process is repeated in triplicate and the mean specific gravity is used in subsequent dosage determinations. The sample is measured by pipette into pre-tared Erlenmeyer flasks to yield final replicate sample concentrations of 250 mg/l, 500 mg/I, and 750 mg/l. Approximately 200 ml of dilution water is added to each flask. The flasks are capped with parafilm, a neoprene stopper and aluminum fail and mechanically shaken for six hours. TOXICITY TESTING Dosing Test Aquaria After shaking, the samples are dosed into the appropriately marked aquaria containing approximately 9 liters of dilution water. Dilution water is then added to the 10 liter mark to yield a final volume of 10 liters for all test conditions. Reconstituted softwater (dilution water only) controls are established as a quality assurance measure.All test conditions and controls are run concurrently. Initial Water Quality Measurements Prior to the addition of the test fish, preliminary water quality measurements are taken for dissolved oxygen and pH to determine if adjustment is necessary(Polisini 1988). An initial hardness and alkalinity test analysis is performed on the control and the 750 mg/l concentrations. MBC Applied Environmental Sciences, 3000 Redhill Avenue, Costa Mesa, California 92626