Prudent Practices in the Laboratory Handling and Management of Chemical Hazards, Updated Version (2011) / Chapter Skim
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6 Working with Chemicals
6 Working with Chemicals
Pages 105-146
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From page 105... ...
6 Working with Chemicals 6.A INTRODUCTION 107 6.B PRUDENT PLANNING 107 6.C GENERAL PROCEDURES FOR WORKING WITH HAZARDOUS CHEMICALS 108 6.C.1 Personal Behavior 108 6.C.2 Minimizing Exposure to Hazardous Chemicals 108 6.C.2.1 Engineering Controls 108 6.C.2.2 Avoiding Eye Injury 108 6.C.2.3 Avoiding Ingestion of Hazardous Chemicals 109 6.C.2.4 Avoiding Inhalation of Hazardous Chemicals 110 6.C.2.5 Avoiding Injection of Hazardous Chemicals 111 6.C.2.6 Minimizing Skin Contact 111 6.C.3 Housekeeping 113 6.C.4 Transport of Chemicals 114 6.C.5 Storage of Chemicals 114 6.C.6 Use and Maintenance of Equipment and Glassware 114 6.C.7 Working with Scaled-Up Reactions 115 6.C.8 Responsibility for Unattended Experiments and Working Alone 116 6.C.9 Chemistry Demonstrations and Magic Shows 116 6.C.10 Responding to Accidents and Emergencies 117 6.C.10.1 General Preparation for Emergencies 117 6.C.10.2 Handling the Accidental Release of Hazardous Substances 117 6.C.10.3 Notification of Personnel in the Area 117 6.C.10.4 Treatment of Injured and Contaminated Personnel 117 6.C.10.5 Spill Containment 120 6.C.10.6 Spill Cleanup 120 6.C.10.7 Handling Leaking Gas Cylinders 120 6.C.10.8 Handling Spills of Elemental Mercury 121 6.C.10.9 Responding to Fires 121 6.D WORKING WITH SUBSTANCES OF HIGH TOXICITY 122 6.D.1 Planning 122 6.D.2 Experiment Protocols Involving Highly Toxic Chemicals 123 6.D.3 Designated Areas 123 6.D.4 Access Control 123 6.D.5 Special Precautions for Minimizing Exposure to Highly Toxic Chemicals 124 6.D.6 Preparing for Accidents with and Spills of Substances of High Toxicity 125 6.D.7 Storage and Waste Disposal 125 6.D.8 Multihazardous Materials 125 105
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From page 106... ...
106 PRUDENT PRACTICES IN THE LABORATORY 6.E WORKING WITH BIOHAZARDOUS AND RADIOACTIVE MATERIALS 126 6.E.1 Biohazardous Materials 126 6.E.2 Radioactive Materials 127 6.F WORKING WITH FLAMMABLE CHEMICALS 127 6.F.1 Flammable Materials 129 6.F.2 Flammable Liquids 129 6.F.3 Flammable Gases 129 6.F.4 Catalyst Ignition of Flammable Materials 130 6.G WORKING WITH HIGHLY REACTIVE OR EXPLOSIVE CHEMICALS 130 6.G.1 Overview 130 6.G.2 Reactive or Explosive Compounds 131 6.G.2.1 Protective Devices 131 6.G.2.2 Personal Protective Apparel 132 6.G.2.3 Evaluating Potentially Reactive Materials 132 6.G.2.4 Determining Reaction Quantities 132 6.G.2.5 Conducting Reaction Operations 133 6.G.3 Organic Peroxides 133 6.G.3.1 Peroxidizable Compounds 134 6.G.3.2 Peroxide Detection Tests 134 6.G.3.3 Disposal of Peroxides 134 6.G.4 Explosive Gases and Liquefied Gases 135 6.G.5 Hydrogenation Reactions 135 6.G.6 Materials Requiring Special Attention Because of Toxicity, Reactivity, Explosivity, or Chemical Incompatibility 135 6.G.7 Chemical Hazards of Incompatible Chemicals 140 6.H WORKING WITH COMPRESSED GASES 140 6.H.1 Chemical Hazards of Compressed Gases 140 6.H.2 Specific Chemical Hazards of Select Gases 140 6.I WORKING WITH MICROWAVE OVENS 141 6.J WORKING WITH NANOPARTICLES 141 6.J.1 Controls for Research and Development Laboratory Operations That Utilize or Synthesize Nanomaterials 141 6.J.1.1 Nanomaterial Work Planning and Hazard Assessment 142 6.J.1.2 A Graded Approach to Determining Appropriate Nanomaterial Controls 142 6.J.1.3 Engineering Controls for Nanomaterials Research 143
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From page 107... ...
Prudent execution of experiments requires not only Use laboratory chemical hoods and other vensound judgment and an accurate assessment of the tilation devices to prevent exposure to airborne risks involved in the laboratory, but also the selection of substances whenever possible. appropriate work practices to reduce risk and protect • Do not underestimate hazards or risks.
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From page 108... ...
. (See Chapter 5, section 5.F for include laboratory chemical hoods and other ventiladetailed instructions on the transport of chemicals and tion systems, shields, barricades, and interlocks.
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From page 109... ...
Never worn when there is a risk of splashing hazardous wear gloves or laboratory coats outside the laboratory materials or flying particles. or into areas where food is stored and consumed, and • Because chemical splash goggles offer little pro always wash laboratory apparel separately from per tection to the face and neck, full-face shields sonal clothing.
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this book, the OSHA Respiratory Protection Standard • Keep laboratory chemical hoods clean and clear; (29 CFR § 1910.134) , and ANSI Standard Z88.2-1992.
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When accompanied by a cap, syringe needles terials should not be removed from the immediate should be placed onto syringes with the cap in place area (usually a laboratory chemical hood) in which and remain capped until use.
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• 4H® or Silvershield® is a registered trademark 6.C.2.6.1.1 atex Gloves L of North Hand Protection; it is highly chemical resistant to many different class of chemicals. Although natural rubber latex gloves can be used • Viton®, a registered trademark of DuPont, is a as protective equipment to prevent transmission of highly chemical-resistant but expensive synthetic infectious diseases and for skin protection against con elastomer.
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From page 113... ...
dispose of as hazardous waste. • Return all equipment and laboratory chemicals to To prevent chemical exposure from spilled materi- their designated storage location at the end of als in the laboratory, wear shoes that cover the entire the day.
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For peroxide formers, write the Remove broken glass, spilled chemicals, and pa- test history and date of discard on the label as well. per litter from benchtops and laboratory chemical Keep only small quantities (<1 L)
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From page 115... ...
Cuts from forcing chemical fume hood. There was no fire.
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be left on, and signs should be posted identifying the • Gaseous byproducts are formed. nature of the experiment and the hazardous substances • A reaction is exothermic.
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If a highly toxic gas or volatile material is the institution's Chemical Hygiene Plan. Laboratory released, the laboratory should be evacuated and supervisors should ensure that all trained laboratory personnel posted at entrances to prevent others from personnel are familiar with this information.
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is used should establish special dered separately from other clothing. procedures for accidental exposures, and laboratory personnel should be trained in these emergency proce- For splashes into the eye: dures.
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3. Save all chemical containers and a small amount of vomitus, if possible, for analysis.
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. For cleanup, ap 6.C.10.5 Spill Containment propriate PPE, including gloves, chemical splash All personnel who work in a laboratory in which goggles, and (if necessary)
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Hands-on experience organizations have established cleanup standards for with common types of extinguishers and the proper laboratory spills. These stringent standards ensure the choice of extinguisher should be part of basic laborasafety of trained laboratory personnel, students, and tory training.
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From page 122... ...
on a list of highly toxic chemicals to determine the level • Extinguish small fires involving reactive metals of the risk; under certain conditions, chemicals not on and organometallic compounds (e.g., magne- these lists may react to form highly toxic substances. sium, sodium, potassium, and metal hydrides)
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From page 123... ...
which may be a laboratory chemical hood or gloveThey also need to be consulted for guidance regarding box, a portion of a laboratory, or the entire laboratory those chemicals that are regulated by federal, state, module, should be recognized by everyone in the laboand local agencies or by institutional policy. Thor ratory or institution as a place where special training, oughly review the wealth of information available in precautions, laboratory skill, and safety discipline are the MSDS, the literature, and toxicological and safety required.
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From page 124... ...
Additionally, rooftop access may need to be eliminated durequipment should include interlocks that shut down ing certain operations or, when rooftop access is experiments by turning off devices such as heating required, work with highly toxic materials must baths or reagent pumps, or that close solenoid valves not be allowed. (See Chapter 9, section 9.C, for if cooling water stops flowing through an apparatus or detailed discussion on laboratory chemical hoods if airflow through a laboratory chemical hood becomes and environmental control.)
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From page 125... ...
The procedures laboratory personnel should be trained in their proper should address methods for decontamination of all use. These kits should be marked, contained, and laboratory equipment that comes into contact with sealed to avoid contamination and to be accessible in highly toxic chemicals.
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3. Wear personal protective clothing in the labo BSL 2 is appropriate for handling a broad spectrum ratory (e.g., eye protection, laboratory coats, of moderate-risk agents that cause human disease gloves, and face protection)
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Prudent practices for working with radioactive materials are similar to those needed to Flammable and combustible materials are a common reduce the risk of exposure to toxic chemicals (section laboratory hazard. Always consider the risk of fire 6.C has similar information)
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VIGNETTE 6.3 For example, secondary containment can be a large Solvent fire tray in which the apparatus stands. This precaution is particularly important for distillations and similar A researcher placed a 1,000-mL beaker containoperations where the breakage of the still pot would ing 60 g of a reagent on a magnetic stirrer located result in the release of large quantities of flammable in the chemical fume hood.
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Transfers should begins. In addition, emergency response plans must be carried out only in laboratory chemical hoods or in address these substances and their special hazards.
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Palladium or platinum on carbon, platinum ox A heavy transparent plastic explosion shield should be ide, Raney nickel, and other hydrogenation catalysts in place to provide extra protection in addition to the should be filtered carefully from hydrogenation re laboratory chemical hood window. action mixtures.
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On benches and laboratory chemical hoods, nitrogen (N2) or argon when the regulator is incorrectly a 0.25-in.-thick acrylic sliding shield, which is screwed
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Armored laboratory chemical hoods or barricades made with thick (1.0 in.) poly(vinyl butyral)
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with unusually low stability that makes them among • To minimize the rate of decomposition, store perthe most hazardous substances commonly handled oxides at the lowest possible temperature consisin laboratories, especially as initiators for free-radical tent with their solubility or freezing point. Do not reactions.
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Note that these strips must be air dried until the solvent evaporates and exposed to moisture for proper indication and quantification. 6.G.3.1 Peroxidizable Compounds • Add 1 to 3 mL of the liquid to be tested to an equal Certain common laboratory chemicals form perox- volume of acetic acid, add a few drops of 5% aqueides on exposure to oxygen in air.
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(especially heavy metal salts) , can be explosive and For example, most preparative hydrogenations of shock sensitive.
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From page 136... ...
Because the cobalt ether solution of diazomethane is rendered harmless salts used as moisture indicators in some drying agents by dropwise addition of acetic acid. may be extracted by some organic solvents, the use Diethyl and other ethers, including tetrahydrofuran of these drying agents should be restricted to drying and 1,4-dioxane and particularly the branched-chain gases.
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From page 137... ...
In contrast to the imme diate effects of concentrated HF, the onset of effects of contact with more dilute solutions or their vapors may be delayed. Skin contact with acid concentrations in VIGNETTE 6.4 the 20% to 50% range may not produce clinical signs Fluorine inhalation or symptoms for 1 to 8 hours.
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If cedures involved. calcium gluconate gel is unavailable, continue • Only use HF in a chemical hood.
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Disassembly of such chemical hoods must be form highly explosive nitrate esters (e.g., nitroglycer- preceded by washing the ventilation system to remove ine) from reaction with nitric acid.
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To avoid such Gases explosions, vent the still pot with nitrogen, cool it before venting, or restore pressure slowly. Sudden vent Compressed gases expose laboratory personnel ing may produce a shock wave that explodes sensitive to both chemical and physical hazards.
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Chlorine trifluoride reacts vigorously with water 6.I WORKING WITH MICROWAVE OVENS and most oxidizable substances at room temperature, frequently with immediate ignition. It reacts with most Do not use domestic microwave ovens for laboratory metals and metal oxides at elevated temperatures.
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solid materials with embedded nanostructures, engineering controls, 2. solid nanomaterials with nanostructures fixed to identification of appropriate PPE, the material's surface, training plans for laboratory personnel, 3.
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for laboratory personnel. If it is not feasible to duct HEPA-filtered treated exhaust air outside the building, follow the guid 6.J.1.3.2 entilation Preferences V ance in ANSI Z9.7-2007, American National Standard To minimize laboratory personnel exposure, conduct for Recirculation of Air from Industrial Process Exhaust any work that could generate engineered nanoparticles Systems, and conduct a hazard assessment to identify in an enclosure that operates at a negative pressure appropriate engineering controls.
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Insofar as practicable, maintain all working to the type and level of hazard. Do not consider face surfaces (i.e., benches, glassware, apparatus, laboratory shields or safety glasses to provide sufficient protec chemical hoods, support equipment)
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. Transfer engineered nanomaterial samples between Laboratory and support personnel who risk potenworkstations such as laboratory chemical hoods, tial exposure to engineered nanoparticles should be gloveboxes, furnaces in closed labeled containers given training on the risks of exposure and on safe (e.g., marked zip-lock bags)
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From page 146... ...
and to the labora- • cleaning of potentially contaminated surfaces, tory's policies concerning prudent material handling. • disposal of spilled nanoparticles, and Training should cover requirements and recommen- • use of respirators, if applicable.
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