Alterations of serum glycoproteins--possible biologic markers of tumor-host responsiveness.

Chloride is commonly assayed in the clinical laboratory with a mercuric thiocyanate reagent. For example, the Technicon chloride color reagent for the SMA 6/60 contains 400 mg of Hg per liter (ppm), and the waste solution contains 130 mg/L (confirmed by analysis), generated at the rate of 300 mL/h. In our laboratory we accumulate 60 L of waste per month, containing almost 10 g of Hg. It is undesirable to allow such quantities to escape into the environment , but the volume of waste and its liquid nature make its safe disposal difficult. Technicon advises precipitation of the mercury with thioacetamide, followed by filtration. Thioacetamide is a potent carcinogen and shouldnotbe used in the clinical laboratory, nor should thioace-tamide-containing filtrates be released intothe environment. Pragay (1) suggests treatment with NaOH, Na2CO3, and metallic zinc, resulting in 99% precipitation of the mercury. For starting concentrations greater than 100 mg/L he advises double treatment of the solution, a tedious procedure. In any case the final supernatant Hg concentration is of the order of 1 mg/L. Present Environmental Protection Agency standards (2) allow no more than 2 tg of Hg per liter in effluent water. This would require a dilution factor of 6 X i0 for untreated waste or 500 for waste treated with metallic zinc. Even distribution of the untreated waste throughout our hospital's total waste-wateroutput of 8 x 106 L per month would resultin an Hg concentration of 1.2 g/L, uncomfortably close tothe presentguidelines. I have adaptedthe method of Hautala and MacDonald (3) tothetreatment of laboratory wasteand consistently obtain residual Hg concentrations of <10 tgfL. Waste is collected, and placedin a 30-gallon (120-L) plastic trash bin lined with a heavy-duty polyethylene garbage bag. When 100 L accumulates, a solution of 300 g of technical-grade NaOH and 350 g of technical-grade (60%) Na2S in 2 L is added, and the mixture is stirred thoroughly. The final pH of the mixture should exceed 7.0. After 48 h to one week, the supernate is removed with a water aspirator (ensuring dilution). Completeness of precipitation can be checkedby adding a few drops of Na2S solution to the supernate. The black sludge residue (2-5 L) is removed with the garbage bag and disposed of with other solid toxic waste. The residual supernatant concentration of three consecutive batches of waste treated this way has been 8.9, 5.0, and 10.0 tgfL. The procedure may be scaled up or …