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Chemical Safety

A wide variety of hazardous chemical and biological agents are used in laboratories. Therefore, it is required to undergo proper orientation to be aware of possible hazards/accidents.

Basics

  1. Fig: Learn to read MSDS. Maintain a file wiith hardcopies of MSDS

    Before a researcher begins to work in a laboratory, he/she must be made aware of potential hazards (chemicals, lasers, autoclaves, etc.) associated with the laboratory by the lab incharge.

  2. All researchers are responsible to teach themselves about the hazards posed by the chemicals in their vicinity. If using a material, the researcher should also know the safe way to store, handle, and dispose-off the hazardous chemical. If you do not know, ask someone who does or read the MSDS.
  3. All labs are expected to maintain a clearly labeled folder with hard copies of MSDSs of all the  chemicals in the lab. The folder must be stored in a visible location, preferably near the door. This serves as the inventory of chemicals stored in labs.
  4. Material Safety Data Sheets (MSDSs) must be reviewed for product specific handling, storage, and  disposal information.
  5. Become familiar with the location of fire extinguishers, spill kits, and first-aid boxes in your area.  Familiarize yourself with their use. All laboratories with heavy hazardous chemical use must have access to a spill kit.
  6. Before finishing ensure that the work bench and work areas are clean and that all waste chemicals are properly removed and disposed. Any chemical that are to be leftover must be clearly labelled. There should also be a note with the user name, phone number, and expected time of return.
  7. All chemical bottles must be properly labeled. Custom mixtures need to have the IISc chemical label (see Appendix).
  8. All chemical work must be done inside fume hoods. Do not open chemical bottles outside
    fume hoods.
  9. Chemical and biological waste should be segregated, labeled (using IISc Waste Label, see
    Appendix), and appropriately disposed-off.
  10. It must be reemphasized, that no set of rules can substitute for common sense and a professional attitude toward laboratory safety.

Special Precautions for Hydrogen Fluoride

  1. Hydrogen fluoride causes excruciatingly painful burns. Apron, gloves, and a face shield should always be worn when handling these chemicals.
  2. If there is inorganic fluorides in lab, there should be a 2.5% calcium gluconate ointment nearby.

Chemical Hood Usage

  1. Hoods use air-flow to reduce exposure to fumes. Check the anemometer to ensure good air flow before using a hood.
  2. Don’t do anything that obstructs air-flow in the fume hood. E.g. don’t store chemicals or cover vents.

    Fig: Good practices to follow whle working with fume hoods. Never put your head inside. Don’t use hoods as storage. Kepp sash as low as possible.

  3. Keep the sash of hood as low as possible. This prevents the vapors from back-flowing.
  4. Chemicals must be placed at least 6 inches inside the face of the hood.
  5. The user should always remain outside the hood. Never peer inside.

Chemical Transport and Storage

  1. Don’t carry chemicals in hands. Transport chemicals in bottle carriers, carts, buckets, etc.
  2. Safety cabinets are best for storage of chemicals. Liquid chemicals cannot be stored in wooden cupboards or in easily flammable materials, like cardboard boxes.

    Fig: Safe transport of chemical requires trays, buckets and bottle carriers.

  3. Acids, bases and oxidizers must be stored with a secondary containment (to contain the spill in case the first container ruptures). Corrosion resistant plastic trays are a lowcost option for secondary containment.
  4. Large bottles and bottles containing toxic, flammable, or corrosive liquids should be stored on shelves below eye level (maximum 5 feet).
  5. Volatile or unstable materials may be stored in a flammable rated refrigerator only in properly sealed containers. Never store flammable solvents (ether, benzene) in the refrigerator in open containers (beakers).
  6. Food or drink should never be stored in a laboratory refrigerator or freezer. A “No food/drink” (see appendix) is required on all laboratory refrigerators.
  7. Label all open chemical bottles samples with the contents, owner’s name, and date of preparation. Commercially obtained samples should be dated on the day they were opened.
  8. Be careful with materials that may form peroxides (diethyl ether, tetrahydrofuran, dioxane). Opened containers of these materials should be discarded within one year of opening. All such containers should be dated upon receipt and upon opening.
  9. Never leave an unlabeled bottle of “something” behind when you depart.
  10. Always store the four classes of chemicals, acids, bases, solvents and oxidizers, separately. If there is an issue of space, solvents and basses can be stored together, and acids and peroxides can be stored together. Solvents must NEVER be placed along with oxidants and acids.
  11. Never add water to acid. Always add acid to water.

Waste Disposal

  1. Material should be placed into compatible storage containers with secure screw-on tops and labeled with the “IISc Waste Label” (see appendix).
  2. In general waste must be stored in the type of container in which the component materials were purchased (glass, plastic or metal). However, metal cans should not be used for acidic and corrosive solutions (alkali, acid, etc.). Also, as much as possible avoid glass containers for storage as they can shatter easily.
  3. Small amount of waste can be collected in the labs. Once a month, lab incharges are required to collect all the waste and bring it to the waste collection shed (next the utility building). Only labelled and segregate waste will be collected so please make sure all the rules of segregation and labelling are followed. No mystery chemicals please.

    Fig: Chemical waste compatibility. From uhs.virginia.edu

Waste segregation

Hazardous waste needs to be segregated and disposed in the following manner to comply with the
departmental waste management policy.

Chemical segregation

  1. Acids + solvents mixture can spontaneously ignite. Never store/leave a solvent + acid mixture in the lab unattended. If you do happen to make such a solution, segregate it and take it outside of the building to the waster shed.
  2. Acidic waste with fluoride ions must be collected separately in plastic containers, e.g. dilute hydrofluoric acid, ammonium fluoride and buffered-oxide etch.
  3. Acidic wastes which contain toxic metal salts (Cr, Pb, etc.) cannot be buried in a chemical landfill, so must be collected separately.
  4. Acid waste that does not contain metallic toxins or fluoride and have a pH>4 can be disposed into the drain with copious amounts of water
  5. Acid waste that does not contain metallic toxins or fluoride and have a pH<4 must be separately collected in plastic containers. IISc does not allow individuals to neutralize acids.
  6. Acids + oxidizers react and evolve gas. So unattended acids+oxidizer mixtures present an explosion hazard — in extreme cases plastic bottle can burst spraying acid everywhere. Fresh acids+oxidizer mixtures must be collected separately and kept inside the fume hood for 1 day. This allows time for the reaction to complete and gasses to escape. Nitric acid is both a strong acid and an oxidizer so solutions containing HNO3 it should be treated as an acid+oxidizer.
  7. Solvents + oxidizer mixture can also spontaneously ignite. Never store/leave a solvents + oxidizer mixture in the lab unattended. If you do happen to make such a solution, segregate it and take it outside of the building to the waste shed.
  8. Base + solvent mixtures also evolve gasses. So unattended base+oxidizer mixtures present an explosion hazard — in extreme cases plastic bottle can burst spraying base everywhere. Fresh base+oxidizer mixtures must be collected separately and kept inside the fume hood for 1 day. This allows time for the reaction to complete and gasses to escape.

    Fig: General chemical waste disposal guidelines. from Wikimedia.org

  9. Solvents must be separately collected in plastic or metal containers, e.g. benzene, ether, ethyl acetate, acetone, alcohols, hydrocarbons, etc.
  10. Non-toxic basic waste with a pH<10 can be disposed into the drain with copious amounts of water
  11. Basic waste with pH > 10, must be separately collected in plastic container. IISc does not allow individuals to neutralize bases. If they do not have any oxidizer, bases can be stored with solvents.
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