Laboratory Equipment Flashcards
Where must you keep explosive chemicals that require cooler temperatures in a lab?
Lab fridges encased with metal housing and with wiring and controls outside the chamber.
How do you maintain the lab fridges?
Frequent temperature checks, cleaning, defrosting, checking door gasket for mold and proper sealing, and vacuum condenser.
What is the standard fridge temperature?
4c
What is the lab freezer temperature?
-70c and -20c
What do water baths do?
They provide constant temperature by circulating convention currents.
What are water-jacketed incubators?
More evenly distributed heat and rapid temperature recovery due to convention air flow
What is the difference between an oven and an incubator?
Ovens have higher temperatures
What are biological safety cabinets (BSC)?
Workspace that prevents exposure to infectious aerosols
How do BSC work?
HEPA filters filter out microbes
What does HEPA stand for?
High Efficiency Particulate Air
What is the standard efficiency of a HEPA filter?
Removing particles 0.3 um in size
What are HEPA filters made of?
Pleated glass and paper
What are UV light used for?
It disinfects air and contaminated surfaces that can’t be reached by disinfectants
What is an example of a biological safety cabinet class II?
Laminar flow safety cabinet
Laminar flow safety cabinet is the most commonly used for handling infectious material. (T/F)
True
How does the laminar flow safety cabinet work?
Air flow that protect the surface from airborne microorganisms and prevents infectious organisms from escaping
What are fume hoods used for?
Chemical labs to draw away dangerous fumes, gases or vapours
How long do you turn on the air before and after using the fume hood?
15 minutes
What is a centrifuge for?
To separate substances by accelerating gravity
What is RCF?
Relative centrifugal force
What is RCF describing?
The force required to separate two phases
What is the unit for RCF?
G forces (g) - the number of times greater than the force of gravity
What is the formula for RCF?
RCF = Krn^2
What is the value of K in the RCF formula?
K = 1.118 x 10^-5 (when r is in cm)
How is the radius (r) measured for RCF?
From the centre of the rotation to the bottom of the tube
What is the n in the RCF formula?
It is the speed of rotation of the rotor in rpm.
What is the most effective way to increase RCF?
Increasing rpm
Where is the maximum RCF?
The force at the bottom of the tube
Where is the minimum RCF?
The force at the surface of the liquid
What is a device that can be used to determine RCF?
Nomograph
What influences the time required to separate mixtures of different densities?
- rotor speed
- radius of the rotor
- depth of liquid in the tube
What decreases the time needed to centrifuge?
- if you increase the speed or the radius
- if you decrease the depth do the liquid
What’s the difference between the centrifuge requirements for serum/plasma samples and urine samples?
Serum/plasma need to be spun at higher RCF for longer to make sure the cells are spun to the bottom.
Urine samples are centrifuged are a lower RCF for less time to make sure cell components are intact for microscopy.
What does pivotal axis mean?
It is the line across the two points of the trunnion rings that allow the bucket to swing.
What’s the main hazard associated with the use of a centrifuge?
Dispersion of aerosols
What helps control aerosol dispersions in a centrifuge?
- sealed dome shields
- safety trunnion cups
- auto locks
What do electronic balances use to counter balance the load?
Electromagnetic force
How does an electrical balance work?
The pan is connected to a coil that a current goes through. The weight of the load is determined by the voltage of the current as it is proportional to the weight of the load.
What are top load balances used for?
Preparation of reagents, stains and less accurate work
What’s the difference between top load balances and analytical balances?
Top loads weighs to 2 decimal places while analytical weighs to 4 decimal places
What does pH stand for?
Potential hydrogen
What does pH meters measure?
The hydrogen ion concentration in a solution
When do solutions have higher pH?
When they contain less H+ ions
What is a combination electrode?
Reference electrode + indicator electrode
What is the definition of potential?
It’s the difference in charge separated by a barrier
What does the reference electrode do?
It produces a constant potential by releasing a gradual flow of KCl, by the porous plug, into the solution
How does the indicator electrode work?
The glass surrounding it attracts H+ ions. If the number of hydrogen ions in the solution is different than the number of hydrogen ions on the inside of the indicator, a potential charge is produced.
How is pH determined by the pH meter?
It is the difference between the potential produced by the indicator electrode and the constant potential at reference electrode.
What is the standardized temperature for pH meters?
25c
What does the thermometer got to do with pH?
It enables adjusts for changes to hydrogen ion activity due to temp changes
_ H+ = _ pH = acids
⬆️ H+ = ⬇️ pH = acids
_ H+ = _ pH = bases
⬇️ H+ = ⬆️ pH = bases
What is the appropriate solution to soak pH meters for protein?
1% pepsin/0.1 M HCl for 15 minutes
What is the appropriate solution to soak pH meters for inorganic deposits?
0.1 EDTA for 15 minutes
What is the appropriate solution to soak pH meters for grease?
Detergent or ethanol
