Safety of Equipment in Laboratory: Precautions and Procedures

Read this article to learn about some of the precautions and procedures to be observed with some commonly used laboratory equipment for its safety.

Equipment Safety:

Whenever lab equipment is purchased, preference should be given to equipment that:

i. Limits contact between the operator and hazardous material, and mechanical and electrical energy

ii. Is corrosion-resistant, easy to decontaminate and impermeable to liquids

iii. Has no sharp edges or burrs.

Every effort should be made to prevent equipment from becoming contaminated.

To reduce the likelihood of equipment malfunction that could result in leakage, spill or unnecessary generation of aerosolized pathogens:

i. Review the manufacturer’s documentation. Keep for future reference.

ii. Use and service equipment according to the manufacturer’s instructions.

iii. Ensure that anyone who uses a specific instrument or piece of equipment is properly trained in set-up, use and cleaning of the item.

iv. Decontaminate equipment before it is sent out for repairs or discarded.

The following sections outline some of the precautions and procedures to be observed with some commonly used laboratory equipment.

Centrifuges:

Improperly used or maintained centrifuges can present significant hazards to users. Failed mechani­cal parts can result in release of flying objects, hazardous chemicals and bio-hazardous aerosols. The high speed spins generated by centrifuges can create large amounts of aerosol if a spill, leak or tube breakage occurs.

To avoid contaminating your centrifuge:

i. Check glass and plastic centrifuge tubes for stress lines, hairline cracks and chipped rims before use. Use unbreakable tubes whenever possible.

ii. Avoid filling tubes to the rim.

iii. Use caps or stoppers on centrifuge tubes. Avoid using lightweight materials such as aluminum foil as caps.

iv. Use sealed centrifuge buckets (safety cups) or rotors that can be loaded and unloaded in a biological safety cabinet. Decontaminate the outside of the cups or buckets before and after centrifugation. Inspect O-rings regularly and replace if cracked or dry.

v. Ensure that the centrifuge is properly balanced.

vi. Do not open the lid during or immediately after operation, attempt to stop a spinning rotor by hand or with an object, or interfere with the interlock safety device.

vii. Decant supernatants carefully and avoid vigorous shaking when re-suspending.

When using high-speed or ultra-centrifuges, follow the additional practices:

i. Connect the vacuum pump exhaust to a trap.

ii. Record each run in a logbook, keep a record of speed and run time for each rotor.

iii. Install a HEPA filter between the centrifuge and the vacuum pump when working with bio-hazardous material.

iv. Never exceed the specified speed limitations of the rotor.

Electrophoresis Equipment:

i. Ensure that electrophoresis equipment is properly grounded and has electrical interlocks. Do not bypass safety interlocks.

ii. Inspect electrophoresis equipment regularly for damage and potential tank leaks.

iii. Locate equipment away from high traffic areas, and away from wet areas such as sinks or washing apparatus.

iv. Display warning signs.

Heating Baths, Water Baths:

Heating baths keep immersed materials immersed at a constant temperature. They may be filled with a variety of materials, depending on the bath temperature required; they may contain water, mineral oil, glycerin, paraffin or silicone oils, with bath temperatures ranging up to 300°C.

The following precautions are appropriate for heating baths:

i. Set up on a stable surface, away from flammable and combustible materials including wood and paper

ii. Relocate only after the liquid inside has cooled

iii. Ensure baths are equipped with redundant heat controls or automatic cut-offs that will turn off the power if the temperature exceeds a preset limit

iv. Use with the thermostat set well below the flash point of the heating liquid in use

v. Equip with a thermometer to allow a visual check of the bath temperature.

The most common heating bath used in laboratories is the water bath. When using a water bath:

i. Clean regularly; a disinfectant, such as a phenolic detergent, can be added to the water

ii. Avoid using sodium azide to prevent growth of micro-organisms; sodium azide forms explosive compounds with some metals

iii. Raise the temperature to 90°C or higher for 30 minutes once a week for decontamination purposes

iv. Unplug the unit before filling or emptying, and have the continuity-to-ground checked regularly.

Shakers, Blenders and Sonicators:

When used with infectious agents, mixing equipment such as shakers, blenders, sonicators, grinders and homogenizers can release significant amounts of hazardous aerosols, and should be operated inside a biological safety cabinet whenever possible. Equipment such as blenders and stirrers can also produce large amounts of flammable vapours.

The hazards associated with this type of equip­ment can be minimized by:

i. Selecting and purchasing equipment with safety features that minimize leaking

ii. Selecting and purchasing mixing apparatus with non-sparking motors.

iii. Checking integrity of gaskets, caps and bottles before using. Discard damaged items.

iv. Allowing aerosols to settle for at least one minute before opening containers

v. Covering tops of blenders with a disinfectant-soaked towel during operation, when us­ing bio-hazardous material

vi. When using a sonicator, immersing the tip deeply enough into the solution to avoid creation of aerosols

vii. Decontaminating exposed surfaces after use.

Ovens and Hot Plates:

Laboratory ovens are useful for baking or curing material, off-gassing, dehydrating samples and drying glassware.

i. Select and purchase an oven whose design prevents contact between flammable vapours and heating elements or spark-producing components.

ii. Discontinue use of any oven whose backup thermostat, pilot light or temperature controllers have failed.

iii. Avoid heating toxic materials in an oven unless it is vented outdoors (via a canopy hood, for example).

iv. Never use laboratory ovens for preparation of food for human consumption.

v. Glassware that has been rinsed with an organic solvent should be rinsed with distilled water before it is placed in a drying oven.

Analytical Equipment:

The following instructions for safe use of analytical equipment are general guidelines; consult the user’s manual for more detailed information on the specific hazards:

i. Ensure that installation, modification and repairs of analytical equipment are carried out by authorized service personnel.

ii. Read and understand the manufacturer’s instructions before using this equipment.

iii. Make sure that preventive maintenance procedures are performed as required.

iv. Do not attempt to defeat safety interlocks.

v. Wear safety glasses and lab coats (and other appropriate personal protective equipment’s as specified) for all procedures.

Scintillation Counters:

i. Use sample vials that meet the manufacturer’s specifications.

ii. Keep counters clean and free of foreign materials.

iii. To avoid contaminating the counter and its accessories with radioactivity, change gloves before loading racks in the counter or using the computer keyboard. Verify on a regular basis (by wipe testing) that the equipment has not become contaminated.

Atomic absorption (AA) spectrometers:

Sample preparation for atomic absorption procedures often requires handling of flammable, toxic and corrosive products. Familiarize yourself with the physical, chemical and toxicological proper­ties of these materials and follow the recommended safety precautions. Atomic absorption equip­ment must be adequately vented, as toxic gases, fumes and vapours are emitted during operation.

Other recommendations to follow when carrying out atomic absorption analysis are:

i. Wear safety glasses for mechanical protection.

ii. Check the integrity of the burner, drain and gas systems before use.

iii. Inspect the drain system regularly; empty the drain bottle frequently when running or­ganic solvents.

iv. Allow the burner head to cool to room temperature before handling.

v. Never leave the flame unattended. A fire extinguisher should be located nearby.

vi. Avoid viewing the flame or furnace during atomization unless wearing protective eyewear.

vii. Hollow cathode lamps are under negative pressure and should be handled with care and disposed of properly to minimize implosion risks.

Mass Spectrometers (MS):

Mass spectrometry requires the handling of compressed gases and flammable and toxic chemicals. Consult MSDSs for products before using them.

Specific precautions for working with the mass spectrometer include:

i. Avoid contact with heated parts while the mass spectrometer is in operation.

ii. Verify gas, pump, exhaust and drain system tubing and connections before each use.

iii. Ensure that pumps are vented outside the laboratory, as pump exhaust may contain traces of the samples being analyzed, solvents and reagent gas.

iv. Used pump oil may also contain traces of analytes and should be handled as hazardous waste.

Gas Chromatographs (GC):

Gas chromatography requires handling compressed gases (nitrogen, hydrogen, argon, helium), and flammable and toxic chemicals. Consult product MSDSs before using such hazardous products.

Specific precautions for working with gas chromatographs include:

i. Perform periodic visual inspections and pressure leak tests of the sampling system plumb­ing, fittings and valves.

ii. Follow the manufacturer’s instructions when installing columns. Glass or fused capillary columns are fragile handle them with care and wear safety glasses to protect eyes from flying particles while handling, cutting or installing capillary columns.

iii. Turn off and allow heated areas such as the oven, inlet and detector, as well as connected hardware, to cool down before touching them.

iv. To avoid electrical shock, turn off the instrument and disconnect the power cord at its receptacle whenever the access panel is removed.

v. Turn off the hydrogen gas supply at its source when changing columns or servicing the instrument.

vi. When using hydrogen as fuel (flame ionization FID and nitrogen-phosphorus detectors NPD), ensure that a column or cap is connected to the inlet fitting whenever hydrogen is supplied to the instrument to avoid build-up of explosive hydrogen gas in the oven.

vii. Measure hydrogen gas and air separately when determining gas flow rates.

viii. Perform a radioactive leak test (wipe test) on electron capture detectors (ECDs) at least every 6 months for sources of 50 MBq (1.35 mCi) or greater.

ix. Ensure that the exhaust from (ECDs) is vented to the outside.

x. When performing split sampling, connect the split vent to an exhaust ventilation system or appropriate chemical trap if toxic materials are analyzed or hydrogen is used as the carrier gas.

xi. Use only helium or nitrogen gas, never hydrogen, to condition a chemical trap.

Nuclear Magnetic Resonance (NMR) Equipment:

The superconducting magnet of NMR equipment produces strong magnetic and electromagnetic fields that can interfere with the function of cardiac pacemakers. Users of pacemakers and other implanted ferromagnetic medical devices are advised to consult with their physicians, the pacemaker’s manual and pacemaker manufacturer before entering facilities which house NMR equipment.

Pre­cautions for work with NMR include the following:

i. Post clearly visible warning signs in areas with strong magnetic fields.

ii. Measure stray fields with a gauss meter, and restrict public access to areas of 5 gausses or higher.

iii. The strong magnetic field can suddenly pull nearby unrestrained magnetic objects into the magnet with considerable force. Keep all tools, equipment and personal items con­taining ferromagnetic material (e.g., steel, iron) at least 2 metres away from the magnet.

iv. Though not a safety issue, advise users that the magnetic field can erase magnetic media such as tapes and floppy disks disable credit and automated teller machine (ATM) cards, and damage analog watches.

v. Avoid skin contact with cryogenic (liquid) helium and nitrogen; wear a protective face mask and loose-fitting thermal gloves during Dewar servicing and when handling frozen samples.

vi. Ensure that ventilation is sufficient to remove the helium or nitrogen gas exhausted by the instrument.

vii. Avoid positioning your head over the helium and nitrogen exit tubes.

viii. NMR tubes are thin-walled; handle them carefully and reserve them for NMR use only.

High-pressure Liquid Chromatography (HPLC) Equipment:

HPLC procedures may require handling of compressed gas (helium) and flammable and toxic chemicals. Familiarize yourself with the hazardous properties of these products, as well as recom­mended precautionary measures by referring to MSDSs.

i. Inspect the drain system regularly; empty the waste container frequently when using or­ganic solvents.

ii. Ensure that waste collection vessels are vented.

iii. Never use solvents with auto ignition temperatures below 110°C.

iv. Be sure to use a heavy walled flask if you plan to use vacuum to degas the solvent.

v. Never clean a flow-cell by forcing solvents through a syringe: syringes under pressure can leak or rupture, resulting in sudden release of syringe contents.

vi. High voltage and internal moving parts are present in the pump. Switch off the electrical power and disconnect the line cord when performing routine maintenance of the pump.

vii. Shut down and allow the system to return to atmospheric pressure before carrying out maintenance procedures.

Liquid Chromatography (LC/MS) Equipment:

LC/MS requires the handling of compressed nitrogen and flammable and toxic chemicals. Consult product MSDSs before using them.

Take the following specific precautions for working with LC/ MS equipment:

i. Verify gas, pump exhaust and drain system tubing and connections before each use.

ii. Test the pressure switch for the exhaust line before each use.

iii. Ensure that pumps are vented outside the laboratory.