ο Peroxide test strips, which turn to an indicative color in the presence of peroxides, are available commercially. Note that these strips must be air dried until the solvent evaporates and exposed to moisture for proper operation.
ο Add 1 to 3 mL of the liquid to be tested to an equal volume of acetic acid, add a few drops of 5% aqueous potassium iodide solution, and shake. The appearance of a yellow to brown color indicates the presence of peroxides. Alternatively, addition of 1 mL of a freshly prepared 10% solution of potassium iodide to 10 mL of an organic liquid in a 25-mL glass cylinder produces a yellow color if peroxides are present.
ο Add 0.5 mL of the liquid to be tested to a mixture of 1 mL of 10% aqueous potassium iodide solution and 0.5 mL of dilute hydrochloric acid to which has been added a few drops of starch solution just prior to the test. The appearance of a blue or blue-black color within 1 minute indicates the presence of peroxides.
None of these tests should be applied to materials (such as metallic potassium) that may be contaminated with inorganic peroxides. (See Chapter 6, section 6.G.3, for more information about peroxide testing.)
• Presence of sulfide. Commercial test strips for the presence of sulfide are available, and their use is recommended. If the test strips are not available in the laboratory, the following test can be performed. Warning: This test produces hazardous and odiferous vapors. Use only small quantities of solution for the test and use appropriate ventilation. The test for inorganic sulfides is carried out only when the pH of an aqueous solution of the unknown is greater than 10. Add a few drops of concentrated hydrochloric acid to a sample of the unknown while holding a piece of commercial lead acetate paper, wet with distilled water, over the sample. Development of a brown-black color on the paper indicates generation of hydrogen sulfide.
• Presence of cyanide. Commercial test strips for the presence of cyanide are available, and their use is strongly recommended.
• Presence of halogen. Heat a piece of copper wire until red in a flame. Cool the wire in distilled or deionized water, and dip it into the unknown. Again heat the wire in the flame. The presence of halogen is indicated by a green color around the wire in the flame.
8.B.3 Regulated Chemical Hazardous Waste
An important question for planning within the laboratory is whether a waste is regulated as a hazardous waste, because regulated hazardous waste must be handled and disposed of in specific ways. This determination has important implications that can lead to significant differences in disposal cost. Regulatory definitions often differ from common definitions. EPA defines chemical hazardous waste under the Resource Conservation and Recovery Act of 1978 (RCRA 40 CFR Parts 260-272). EPA and RCRA establish the federal standards for chemical hazardous waste. The U.S. Nuclear Regulatory Commission (USNRC) defines radioactive waste. Hazardous biological waste is regulated less stringently under federal law, but its management is addressed in the Occupational Safety and Health Administration (OSHA) bloodborne pathogens standards and in Biosafety in Microbiological and Biomedical Laboratories (BMBL; HHS/CDC/NIH, 2007a).
Note that, although close attention must be paid to the regulatory definitions and procedures that govern the handling and disposal of waste, primary importance must be given to the safe and prudent handling of all laboratory wastes. Evaluate unregulated wastes and consider special handling if they pose occupational, environmental, or unknown risks.
Chemical waste that is regulated as “hazardous waste” is defined by EPA in either of two ways: (1) waste that has certain hazardous characteristics and (2) waste that is on certain lists of chemicals. The first category is based on properties of materials that should be familiar to all trained laboratory personnel. The second category comprises lists, established by EPA, of certain common hazardous chemicals and chemical wastes. These lists generally include materials that are widely used and recognized as hazardous. Chemicals are placed on these RCRA lists primarily on the basis of their toxicity. See below to determine if waste is hazardous or not.
Regardless of the regulatory definitions of hazard, understanding chemical characteristics that pose potential hazards is a fundamental part of the education and training of laboratory personnel. These characteristics may be derived from knowledge of the properties or precursors of the waste. The characteristics may also be established by specific tests cited in the regulations.
8.B.3.1 Definition of Characteristic Waste
According to federal law, the properties of chemical waste that pose hazards are as follows. Note that