Laboratory safety procedures

 

LABORATORY SAFETY PROCEDURES / GUIDELINES

a)      Proper choice of glassware

General Glass properties:

·         High chemical resistance against many substances: acids, alkalis, organic solvents, saline solutions, and water. The only substances that can destroy glass are hydrofluoric acid, strong alkalis used at high temperatures, and concentrated phosphoric acid. Thus is suitable for reagent and chemical storage.

·         Dimensionally stable: even at high temperatures (think of Pyrex glass)

·         Transparent

Types of glass:

·         Soda-lime glass: eg. AR-Glas is suitable for short exposure to chemicals, and for limited heat stress because of its good physical and chemical properties. Products manufactured from this kind of glass include culture tubes and pipettes.

·         Borosilicate glass: eg. BORO 3.3, BORO 5.0 Once again, this type of glass has good physical and chemical properties. BORO 3.3 has the ability to withstand a high variety of chemicals and temperatures and has good thermal shock and mechanical stability capabilities.

Cleaning of glassware

·         Clean the apparatus in cold water to ensure that any protein residues are removed.

·         Use a bristle brush or scorching pad to remove any material adhering to the surface of the glass.

·         Soaking in detergent or using an ultrasonic bath.

·         Rinse the item in deionized water three times to remove residual detergent.

·         Drain on a rack, and then dry in a clean environment or a hot air oven.

 

Glassware containers include:

·         Beakers are simple cylindrical shaped containers used to hold reagents or samples.

·         Flasks are narrow-necked glass containers, typically conical or spherical, used in a laboratory to hold reagents or samples. Examples flasks include the Erlenmeyer flask, Florence flask, and Schlenk flask.

·         Bottles are containers with narrow openings generally used to store reagents or samples. Small bottles are called vials.

·         Jars are cylindrical containers with wide openings that may be sealed. Bell jars are used to contain vacuums.

·         Test tubes are used by chemists to hold, mix, or heat small quantities of solid or liquid chemicals, especially for qualitative experiments and assays

·         Desiccators of glass construction are used to dry materials or keep material dry.

·         Glass evaporating dishes, such as watch glasses, are primarily used as an evaporating surface (though they may be used to cover a beaker.)

·         Glass Petri dishes are used to culture living cells.

·         Microscope slides are thin strips used to hold items under a microscope.

Glassware used for measurements include:

·         Graduated cylinders are cylindrical containers used for volumetric measurements.

·         Volumetric flasks are for measuring a specific volume of fluid.

·         Burettes are used to disperse precise amounts of liquid reagents.

·         Glass pipettes are used to transfer precise quantities of fluids.

·         Glass Ebulliometers are used to accurately measure the boiling point of liquids.

Other glassware includes:

·         Stirring rods are used to mix chemicals.

·         Condensers are used to cool hot liquids or vapors.

·         Glass retorts are used for distillation.

·         Drying pistols are used to free samples from traces of water, or other impurities.

 

Safety precautions

·         Due to susceptibility to mechanical stress and thermal shock e.g. in an exothermic reaction, make sure you stir and cool, and that the reaction takes place in a suitable vessel.

·         Do not heat volumetric instruments on heating plates or you run the risk of breakage. Ensure there is use of safety devices such as goggles, gloves, and screens.

·         Do not expose glass instruments to sudden temperature changes or to sudden pressure changes.

·         The glass should be properly heated (glass should be heated to a temperature somewhere between the lower and upper annealing point) and cooled so that permissible mechanical loads are not exceeded, and breakage is avoided. Different types of glass show different levels of temperature change resistance.

Quick question: Define annealing temperature in terms of glass manufacturing

 

b)      Flame/fire polishing

Fire polishing is a technique employed in glass fabricating. When a glass rod or tube is cut, it leaves a rough, sharp finish. When a flame is applied to reach the softening point, it seals or “polishes” the end to a smooth, glassy finish or “polish,” thus the term "fire polish".

Importance of fire polishing: Fire polishing the ends of glass tubing and rod will seal small cracks in the end wall, reducing the chance of fractures originating from this source. Fire polishing ends will also reduce cuts and abrasions to you or anything (corks, latex tubing, etc.) Fire polish by rotating the glass tube end in the flame.

Safety precaution: Fire polishing is accomplished by rotating the glass in the flame near the outer edge. Heat the glass until the edges flow into the hemisphere shape on the end. Do not heat to the point of constricting the diameter of the tube.  The glassblower is constantly blowing into the open ends of the apparatus and a sharp edge can cut the lips very severely.

 

c)      Acid dilution procedures

Because the addition of acid to water is highly exothermic, use high temperature Pyrex glassware.

 

d)     Laboratory rules

1. Read through the procedures of each laboratory activity before you start the lab so that you are familiar with them.

2. Know how to locate and use all safety equipment in the laboratory, including the fume hood, emergency shower, first aid kit, fire blanket, fire extinguisher, and eyewash. Also be sure to locate the nearest exit in case of an emergency.

3. Avoid dangerous behavior in the laboratory.

4. Always conduct your experiments with adult supervision.

5. Wear safety goggles when handling all hazardous chemicals, working with an open flame, or when otherwise instructed.

6. Wear an apron or a smock to protect your clothing in the laboratory when using chemicals.

7. Tie back long hair, and secure any loose-fitting clothing.

8. Never eat or drink in the laboratory.

9. Wash your hands before and after each activity in the lab.

10. Keep the work area free of any unnecessary items.

11. Wash all utensils thoroughly before and after each use.

12. Never smell or taste any chemicals unless instructed to do so by your teacher and the experiment instructions.

13. Do not experiment or mix chemicals on your own. Many chemicals in the lab are explosive or dangerous.

14. When using scissors or a scalpel, cut away from yourself and others.

15. When heating substances in a test tube, always point the mouth of the test tube away from yourself and others.

16. Clearly label all containers with the names of the materials you are using.

17. Report all accidents to the teacher immediately, including breakage of materials, chemical spills, and injury.

 

18. Do not pick up broken glass with your hands. Sweep up broken glass with a broom, and dispose of the glass in a container labeled for glass disposal.

19. Never return unused chemicals to their original containers. Follow your teacher’s instructions for the proper disposal and cleanup of all materials.

20. Clean up your equipment and work area before leaving the lab.

21. Be certain that all Bunsen burners, gas outlets, and water faucets are turned off before leaving the lab.

 

e)      Fire safety procedures

The first rule is never panic. Do not run away. Your instructor may to put out the fire before it spreads.   The first 5 minutes of fire-fighting is very important and most fire can be contained within this time. Alert your instructor other workers in the laboratory for help or to seek help. If fire has gone beyond control then quickly alert everybody in the building and leave. Most laboratories fire can be put out with CO2 fire extinguishers. For fires involving active metals or metal hydrides, use dry chemical extinguishers or sand —never use water!

When clothing is on fire, the victim should not run. This merely fans the flame. Either smother the fire by wrapping the victim in a fire blanket/wet coat or douse the fire under the emergency shower.

 

f)       Handling of Chemicals

1)  Respect all chemicals and be cautious when handling them, especially those you know very little about.

2) Corrosive and toxic chemicals must be handled in the fame hood.

3) Laboratory coats and safety glasses must be worn.

4)   Never use your mouth to pipette dangerous liquids- Use a rubber safety bulb for all pipetting purposes.

5)  Do not carry bottles containing corrosive liquids (concentrated acids, bromine etc) by their necks. There are baskets specially made for that purpose.

6)   Do not pour or dispose of hazardous materials in the sink. Labeled residual bottles should be used and kept in the fume cupboard.

7)  Compressed gas cylinders must be properly strapped and not left standing on their own.

 

g)      Eye Safety

1) Wear your laboratory safety goggles when you are working with chemicals, open flame, or any                     substances that may be harmful to your eyes.

2) Know how to use the emergency eyewash system. If chemicals get into your eyes, flush them out with plenty of water for 15 minutes.  Inform your teacher.

 

h)      Clothing Protection

Wear your laboratory apron. It will help to protect your clothing from stains or damage.

 

i)        Glassware Safety

1)   Check glassware for chips or cracks. Broken, cracked, or chipped glassware should be disposed of properly.

 

2) Do not force glass tubing into rubber stoppers. Follow your teacher’s instructions.

 

3) Clean all glassware and air-dry them rather than drying with a towel.

 

j)        Sharp Objects

 

1) Be careful when using knives, scalpels, or scissors.

 

2)  Always cut in the direction away from your body and from others who are nearby.

 

3)  Inform your teacher immediately if you or your partner is cut.

 

 

 

k)      Heating Safety

1)        Turn off heat sources when they are not in use.

2)        Point test tubes away from yourself and others when heating substances in them.

3)        Use the proper procedures when lighting a Bunsen burner.

4)        To avoid burns, do not handle heated glassware or materials directly. Use tongs, test-tube holders, or heat-resistant gloves or mitts.

5)        For heating, use glassware that is meant to be used for that purpose.

6)        When heating flasks or beakers over the laboratory burner, use a ring-stand setup with a square of wire gauze.

7)        Use a water bath to heat solids.

8)        When heating with a laboratory burner, gently move the test tube over the hottest part of the flame.

9)        Do not pour hot liquids into plastic containers.

 

l)        Fire/Explosion Safety

1)        Tie back long hair and roll up long sleeves when working near an open flame. Confine loose clothing.

2)        Do not reach across an open flame.

3)        Know the location and proper use of fire blankets and fire extinguishers.

 

m)    Electrical Safety

1)        Be careful when using electrical equipment.

2)        Check all electrical equipment for worn cords or loose plugs before using.

3)        Keep your work area dry.

4)        Do not overload electric circuits.

5)        Be sure that any electrical cords are not in a place where someone can trip over them.

 

 

n)      Poison

1)        Do not mix any chemicals unless directed to do so in a procedure or by your teacher.

2)        Inform your teacher immediately if you spill chemicals or get any chemicals on your skin or in your eyes.

3)        Never taste any chemicals or substances unless directed to do so by your teacher.

4)        Keep your hands away from your face when working with chemicals.

5)        Wash your hands with soap and water after handling chemicals.

 

o)      Animal Safety

1)        Handle live animals with care. If you are bitten or scratched by an animal, inform your teacher.

2)        Do not bring wild animals into the classroom.

3)        Do not cause pain, discomfort, or injury to an animal.

4)        Be sure any animals kept for observations are given the proper food, water, and living space.

5)        Wear gloves when handling live animals. Always wash your hands with soap and water after handling live animals.

 

p)      Plant Safety

1)        Use caution when collecting or handling plants.

2)        Do not eat or taste any unfamiliar plant or plant parts.

3)        Wash your hands with soap and water after handling plants.

4)        If you are allergic to pollen, do not work with plants or plant parts without using a gauze face mask.