Standard laboratory safe handling/storage requirement

General Principles

  1. Prior to commencing work involving a chemical substance, make sure to refer to its safety data sheet (SDS) and familiarize yourself with its specific hazards. Moreover, the laboratory will provide all employees access to safety data sheets (SDS) for the materials used, either through a group drive/cloud or a binder containing the sheets.
  2. When dealing with a chemical substance, it is imperative to protect yourself by wearing a full-length enclosed lab coat, closed liquid-repellent shoes (not fabric), safety goggles or a face shield, as well as appropriate gloves.
  3. Movement of containers holding hazardous substances between various zones of the laboratory or building should be executed using a suitable cart or plastic container designed to accommodate a single bottle, or by utilizing an appropriate cooler.
  4. Exclusive use of a chemical fume hood is mandatory for handling hazardous chemicals, except for permitted cases involving analytical instruments and materials (diluted solutions) authorized work outside the chemical fume hood, as approved by the laboratory director.
  5. When diluting concentrated acids or bases, it's essential to adhere to the requirement of adding the acid or base to the water, rather than the reverse procedure.
  6. After utilizing a hazardous substance, securely seal the container's lid and store it in an appropriately labeled cabinet. Avoid lifting the bottle by its cap.
  7. Maintain a minimal quantity of necessary chemicals substances at the workstation/hood, sufficient for the task's duration.
  8. Ensure proper labeling of each container (chemical beaker, Erlenmeyer flask, test tube, etc.) containing a, including its name and concentration.
  9. Hazardous liquid chemical substances designated cabinets or on shelves in the laboratory space. All, in the cabinet where liquids and solids are stored, the solids must be stored above the liquids.
  10. It's crucial to maintain proper segregation of chemicals based on their risk groups to prevent potential reactions. Particular attention should be given to segregating flammable substances (such as ethanol/methanol/isopropanol) from oxidizing agents (hydrogen peroxide, bleach, AgNO3), as well as corrosive acids and bases, to ensure safety.
  11. Flammable and explosive materials that require refrigeration shall only be stored in refrigerators designed to prevent explosions. In laboratories where work involving such materials is conducted, appropriately labeled explosion-proof refrigerators will be provided. The label "Do not store flammable/explosive materials in this refrigerator" must be affixed.
  12. The laboratory's director will conduct bi-annual audits of all chemical substances housed within the laboratory, including those stored in hoods and evaporation cabinets. Employees are responsible for disposing of used materials as waste.
  13. It is forbidden to dispose substances such as acidic compounds, bases, organic solvents, and similar materials into the sewage system.
  14. Chemical waste will be collected within designated containers that located in chemical hood. Ensure that each container is properly labeled and accompanied by a leaflet detailing its contained materials. It's important to seal the containers securely. Once full, a department representative from the visibility branch will transport them to the central collection area. (Containers should not be filled beyond 80% capacity.)
  15. Aqua regia and Piranha type materials will remain in the chemical hood until disposal. Contact the visibility branch to arrange for disposal. Piranha waste needs to be placed in an open container within the chemical hood for two weeks before removal. Remember to mark the container with the date of filling.
  16. It's important to ensure the separation of substances that may react violently when combined. Liquid waste should be categorized as follows:
    1. Flammable organic solvents (ethanol, acetonitrile, methanol, etc.) and organic acids like acetic acid.
    2. Inorganic acids such as hydrochloric acid, phosphoric acid, nitric acid.
    3. Inorganic bases.
    4. Halogenated organic solvents (containing F, Cl, Br, I): such as chloroform and methylene chloride.
    5. Inorganic substances like metals/metal salts, hydrogen peroxide, and sodium hypochlorite ("bleach").
  17. Before disposing of chemical waste, make sure to attach an appropriate sticker. You can find stickers for each material on the safety unit website in the Weizmann net application.
  18. Avoid using empty containers/bottles of chemical substances for waste from a different risk category (e.g., organic solvents inside a bottle that was previously used for organic acid).
  19. Processing an empty bottle involves handling volatile chemicals. Any remaining traces need to be eliminated using a chemical hood, ensuring the container bottle dry before transferring it to the designated collection site. In the case of substances with a low vapor pressure (low volatility), thorough emptying of the bottle or container is necessary, followed by two water rinses and dry before transferring it to the designated collection site. A bottle/container containing a substance, which is not identified, will be labeled with a white sticker on which "unknown substance" will be written. The operations branch must be informed of the location of the bottle/container and coordinate collection.
  20. The recommended approach involves disposing of chemicals using their original containers. Additionally, it's imperative not to discard non-aqueous solutions within lab equipment like beakers, flasks, and conical tubes. In cases where utilizing the original container for waste disposal isn't feasible, opting for an HDPE Polyethylene container is ideal due to its remarkable resistance to diverse chemicals such as potent acids/bases, as well as mild oxidants and reducing agents. The WIS warehouse provides a range of HDPE container sizes. Prior to mixing different chemicals in a hazardous waste container, it's vital to assess their chemical compatibility. Mixing incompatible chemicals can result in reactions leading to heat generation, emission of toxic gases, or even explosions.
  21. Lab personnel will gather chemical waste in appropriate labeled containers within the lab, and these containers should then be taken to assigned collection spots within the department. Workers from the Operations Division will retrieve the chemical waste from department waste areas and transport it to the Weizmann Institute's ecological site. Eventually, the waste will be dispatched to the national site in Ramat Hovav.

Guidelines for storing common chemical substances in the laboratory

  1. Flammable organic liquids should be stored separately, either with a buffer or secondary container (a liquid storage container like a plastic tub) placed between the three flammable groups: flammable organic liquids, flammable organic acids, and flammable organic bases.
  2. Toxic organic liquids.
  3. Inorganic acids.
  4. Inorganic bases.
  5. Inorganic oxidizing liquids.

Examples of chemical liquid storage by groups

Type Example
Flammable organic liquids Ethanol, Methanol, Acetone, Petroleum Ether, Diethyl ether, Isooctane, Xylene, Hexane, Acetonitrile, Dimethylformamide (DMF), Dimethyl sulfoxide (DMSO), Isopropyl alcohol, Formalin (formaldehyde), Ethyl acetate, Isoamyl alcohol
Flammable organic acids Acetic acid and Formic acid can be stored in the flammable cabinet, provided they are placed within a secondary container.
Toxic organic liquids Ethylene glycol, Formamide, Chloroform, Acrylamide solution, 2 mercaptoethanol.
Inorganic acids Nitric acid, Hydrochloric acid, Phosphoric acid, Sulfuric acid
Inorganic bases Amine ethanol, Pyridine
Inorganic oxidizing liquids Ammonia solution, Potassium hydroxide solution
  Hydrogen peroxide, Potassium permanganate (KMnO3)


Enhancing the awareness of potential chemical hazards

Enhancing awareness about potential chemical hazards can substantially diminish the likelihood of inappropriate utilization among laboratory staff, newcomers, and visitors.

The following prerequisites are necessary for accurate chemical identification and storage within the laboratory:

  1. Chemical containers must have intact and legible labels that contain information about the substance's associated risks.
  2. Containers filled from the original chemical bottles must be labeled with the substance name and concentration.
  3. Chemical storage areas should be properly labeled according to provided instructions.
  4. Laboratory personnel should have access to MSDS safety sheets and possess knowledge about the associated risks and requisite safety precautions.

Labeling Chemicals

Labeling containers holding chemicals

Containers holding chemicals need to display a label indicating the substance name and its quantity. For instance, acetaldehyde, which is both flammable and carcinogenic, requires appropriate labeling. Moreover, adhere to the following guidelines:

  1. Peroxide-forming chemicals- must be labeled with the opening date. After the expiration date, inspect for peroxide presence (sediment at the container bottom) or dispose of chemical waste (refer to the peroxide-forming chemical list).
  2. Any secondary laboratory vessel or container holding hazardous chemicals should be labeled in accordance with the original container's label.

Working under conditions involving hazardous substances

Permissible Exposure Limits

The head of the research group has the responsibility to ensure that laboratory personnel are not subjected to perilous chemicals beyond the threshold specified in occupational safety regulations governing health and well-being. The acceptable exposure is denoted as TWA (Time Weighted Average) and is measured in units of ppm or mg/m3. TWA signifies the proportion between the average exposure and the scale of the task, standardized to the duration of the work period. 

Special care should be taken to safeguard employees dealing with carcinogenic agents, substances harmful to the reproductive system, and highly toxic chemicals within the laboratory.

Adequate protection against exposure to these substances is assured by adhering to proper procedures and employing safety precautions.

  1. Dedicated workspace:
    1. Use or store highly hazardous materials in an engine area with limited access (chemical hood, bench), and ensure that all workers with access to the laboratory are aware of the risks.
    2. Label all containers, tools, accessories and work tools with an appropriate label.
  2. Measures to prevent the spread of risk factors in the laboratory:
    1. Use a chemical hood in processes where spray or vapors are generated. Make sure that the vapors do not spread in the laboratory space.
    2. Fragile containers (glass containers) must be stored in a combination composed of a chemical-resistant material and in a volume that will contain the liquid and the container will break.
  3. Cleaning/purification processes:
    1. Upon exiting the workspace, take off the lab coat and thoroughly cleanse hands, forearms, facial area, and neck.
    2. Before removing equipment from the work area, ensure that vacuum traps or other apparatus, including glassware, are properly cleaned. Additionally, sanitize the work surface before transitioning to regular tasks.
  4. When handling extremely hazardous chemicals:
    1. Refer to the Safety Data Sheet (SDS) for guidance, acquaint yourself with the perilous characteristics of the substance, and employ suitable safety precautions. Develop a comprehensive plan that encompasses the entire process of working with the material. Contemplate using an alternative to the hazardous substance. It is advisable to seek advice from the safety unit.
    2. In case of malfunctions, exposure, or spills, promptly inform the head of the research group and the institute's central office at 08-9342999 via telephone.
  5. Hazards of a physical nature:
    1. Dealing with materials that pose physical risks necessitates a grasp of their inherent characteristics. Failure to adhere to appropriate safety measures could result in personal harm or damage. Moreover, the combination or storage of certain chemicals is not recommended due to the potential for intense chemical reactions or high levels of toxicity.

Chemical properties categorized by risk groups and corresponding actions

  1. Flammable substances 
    This category of materials indicates the fire risk level. The flash point, or the lowest temperature at which a liquid emits vapors in adequate concentration to form a mixture, defines this parameter.
    When handling materials prone to ignition:
    1. Eradicate potential ignition sources, such as open flames, heated surfaces, sparks from welding or cutting tools, operational electrical apparatus, and static electricity.
    2. Alternatively, store them in containers specifically designed for flammable materials, employing fire-resistant materials, and positioning them in an area isolated from ignition sources.
    3. Ensure secure grounding, particularly when transferring flammable contents from the primary container to a secondary one.
    4. Guarantee the availability of suitable fire extinguishing resources
  2. Oxidizing Agents 
    An oxidizing agent is a substance that usually reacts by removing electrons from other substances, a process known as oxidation.  
    ​​​​​​​Strong oxidizing agents often react vigorously with other compounds, generating heat and possibly gaseous products, which can pressurize a closed container, and which may go on to participate in further reactions. Reactions of strong oxidizing agents with compounds that are known reducing agents are often explosive.
    1. Familiarize yourself with the characteristics of the materials involved in the experiment. Ensure the absence of other hazardous substances in the vicinity.
    2. When anticipating explosive or vigorous chemical reactions, implement shielding or other techniques to isolate the materials or procedure.
  3. Water reactive chemicals
    ​​​​​​​Water reactive chemicals are chemicals that react vigorously with moisture releasing corrosive, toxic, or flammable gases. 
    1. When handling water sensitive chemicals, exercise caution in their utilization and storage, adhering to the manufacturer's instructions (refer to SDS).
    2. When anticipating explosive or vigorous chemical reactions, implement shielding or other techniques to isolate the materials or procedure.
  4. Pyrophoric Substances
    Pyrophoric materials are substances that ignite instantly upon exposure to oxygen. They can also be water-reactive, where heat and hydrogen (a flammable gas) are produced. Examples of such materials include white or yellow phosphorus, Silane, Silicon tetrachloride.
  5. Peroxide Forming Substances (Peroxidizable)
    ​​​​​​​Substances capable of forming peroxides can give rise to molecules containing peroxide groups (ROOH, ROOR) within a sealed container containing various organic solvents. Peroxide compounds tend to decompose at specific temperatures or through reactions with diverse acids, accompanied by the rapid release of heat. Hence, it is imperative to exercise extreme caution when storing the materials mentioned.
    1. The date needs to be inscribed on products prone to peroxide formation both upon receipt and when the container is unsealed.
    2. After a minimum of one year, the generation of peroxides should be examined, and items should be disposed of if necessary.
    3. Avoid opening a container if solid material forms around the lid or at the container's base.
    4. It's advisable to introduce an inhibitor substance against peroxide formation. Some solvents, like butylated hydroxytoluene (BHT), already contain such inhibitors.
    5. Peroxide forming chemicals should be conducted for peroxide formation.
    6. Operate following the prescribed procedures for handling flammable substances.
  6. Light- sensitive substances
    Light- sensitive substances have the potential degrade when directly exposed to the light, resulting in the formation of products that could pose hazards like building up pressure within the container due to gas generation. For instance, in presence of light, chloroform reacts with oxygen to form carbonyl chloride. Carbonyl chloride is a poisonous (highly toxic) gas and is also known as phosgene. while tetrahydrofuran and diethyl ether yield peroxide derivatives under similar conditions.
    To store light-sensitive materials safely, it's advisable to keep them in a cool, dry, dark place within amber bottles or containers that block light infiltration.
  7. Unstable compounds
    ​​​​​​​Refer to substances that can spontaneously release significant energy in standard conditions or in response to shaking, impact, or pressure. Some chemicals can become unstable or may form explosive compounds over a period.
    Particularly perilous are substances that are explosive or easily triggered by shock, including specific peroxide derivatives, compounds oxidized by perchloric acid, dry picric acid, and various substances containing azide groups.
    1. Should there be any suspicion regarding the formation of shock-sensitive materials, it's imperative to promptly inform the safety unit.
    2. The containers of such materials should be labeled with the date of receipt and opening.
    3. When there's a risk of explosion, measures such as blocking or employing protective barriers must be adopted to isolate the materials and processes from potential hazards.
  8. Cryogenic Materials
    A cryogenic material is a material at a very low (or 'cryogenic') temperature. Cryogenic liquids are gases at normal temperature and pressure that are liquefied at very low temperatures. 
    ​​​​​​​Direct contact with cryogenic materials can lead to severe cold burns, frostbite, and retinal damage if the eye is affected. A leak of cryogenic liquids into a room can lead to a displacement of oxygen − resulting in a potential risk of asphyxiation to occupant.
    1. Care must be taken to use clean equipment, especially when working with gaseous or liquid oxygen.
    2. It is mandatory to use protective glasses with side protection. If there is a chance of splashing or spilling, use a full-face shield, an impermeable apron, and closed shoes. Watches, rings, and other jewelry should be removed. Always wear cryogenic protective gloves. 
    3. Tanks and systems containing cryogenic materials must be equipped with a pressure regulator.
    4. Containers and systems containing cryogenic materials must be made of a material resistant to brittleness and breakage.
    5. Glass ampoules or test tubes may explode in contact with cryogenic material. It is recommended to use o screw-on plastic test tubes for freezing radioactive substances, toxic substances, or biological substances. When removing test tubes, it is mandatory to use protective glasses or a face shield.