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MEDL 200 > Laboratory Equipment > Flashcards

Laboratory Equipment Flashcards

1
Q

Where must you keep explosive chemicals that require cooler temperatures in a lab?

A

Lab fridges encased with metal housing and with wiring and controls outside the chamber.

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2
Q

How do you maintain the lab fridges?

A

Frequent temperature checks, cleaning, defrosting, checking door gasket for mold and proper sealing, and vacuum condenser.

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3
Q

What is the standard fridge temperature?

A

4c

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4
Q

What is the lab freezer temperature?

A

-70c and -20c

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5
Q

What do water baths do?

A

They provide constant temperature by circulating convention currents.

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6
Q

What are water-jacketed incubators?

A

More evenly distributed heat and rapid temperature recovery due to convention air flow

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7
Q

What is the difference between an oven and an incubator?

A

Ovens have higher temperatures

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8
Q

What are biological safety cabinets (BSC)?

A

Workspace that prevents exposure to infectious aerosols

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9
Q

How do BSC work?

A

HEPA filters filter out microbes

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10
Q

What does HEPA stand for?

A

High Efficiency Particulate Air

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11
Q

What is the standard efficiency of a HEPA filter?

A

Removing particles 0.3 um in size

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12
Q

What are HEPA filters made of?

A

Pleated glass and paper

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13
Q

What are UV light used for?

A

It disinfects air and contaminated surfaces that can’t be reached by disinfectants

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14
Q

What is an example of a biological safety cabinet class II?

A

Laminar flow safety cabinet

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15
Q

Laminar flow safety cabinet is the most commonly used for handling infectious material. (T/F)

A

True

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16
Q

How does the laminar flow safety cabinet work?

A

Air flow that protect the surface from airborne microorganisms and prevents infectious organisms from escaping

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17
Q

What are fume hoods used for?

A

Chemical labs to draw away dangerous fumes, gases or vapours

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18
Q

How long do you turn on the air before and after using the fume hood?

A

15 minutes

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19
Q

What is a centrifuge for?

A

To separate substances by accelerating gravity

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20
Q

What is RCF?

A

Relative centrifugal force

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21
Q

What is RCF describing?

A

The force required to separate two phases

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22
Q

What is the unit for RCF?

A

G forces (g) - the number of times greater than the force of gravity

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23
Q

What is the formula for RCF?

A

RCF = Krn^2

24
Q

What is the value of K in the RCF formula?

A

K = 1.118 x 10^-5 (when r is in cm)

25
Q

How is the radius (r) measured for RCF?

A

From the centre of the rotation to the bottom of the tube

26
Q

What is the n in the RCF formula?

A

It is the speed of rotation of the rotor in rpm.

27
Q

What is the most effective way to increase RCF?

A

Increasing rpm

28
Q

Where is the maximum RCF?

A

The force at the bottom of the tube

29
Q

Where is the minimum RCF?

A

The force at the surface of the liquid

30
Q

What is a device that can be used to determine RCF?

A

Nomograph

31
Q

What influences the time required to separate mixtures of different densities?

A
  • rotor speed
  • radius of the rotor
  • depth of liquid in the tube
32
Q

What decreases the time needed to centrifuge?

A
  • if you increase the speed or the radius

- if you decrease the depth do the liquid

33
Q

What’s the difference between the centrifuge requirements for serum/plasma samples and urine samples?

A

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.

34
Q

What does pivotal axis mean?

A

It is the line across the two points of the trunnion rings that allow the bucket to swing.

35
Q

What’s the main hazard associated with the use of a centrifuge?

A

Dispersion of aerosols

36
Q

What helps control aerosol dispersions in a centrifuge?

A
  • sealed dome shields
  • safety trunnion cups
  • auto locks
37
Q

What do electronic balances use to counter balance the load?

A

Electromagnetic force

38
Q

How does an electrical balance work?

A

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.

39
Q

What are top load balances used for?

A

Preparation of reagents, stains and less accurate work

40
Q

What’s the difference between top load balances and analytical balances?

A

Top loads weighs to 2 decimal places while analytical weighs to 4 decimal places

41
Q

What does pH stand for?

A

Potential hydrogen

42
Q

What does pH meters measure?

A

The hydrogen ion concentration in a solution

43
Q

When do solutions have higher pH?

A

When they contain less H+ ions

44
Q

What is a combination electrode?

A

Reference electrode + indicator electrode

45
Q

What is the definition of potential?

A

It’s the difference in charge separated by a barrier

46
Q

What does the reference electrode do?

A

It produces a constant potential by releasing a gradual flow of KCl, by the porous plug, into the solution

47
Q

How does the indicator electrode work?

A

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.

48
Q

How is pH determined by the pH meter?

A

It is the difference between the potential produced by the indicator electrode and the constant potential at reference electrode.

49
Q

What is the standardized temperature for pH meters?

A

25c

50
Q

What does the thermometer got to do with pH?

A

It enables adjusts for changes to hydrogen ion activity due to temp changes

51
Q

_ H+ = _ pH = acids

A

⬆️ H+ = ⬇️ pH = acids

52
Q

_ H+ = _ pH = bases

A

⬇️ H+ = ⬆️ pH = bases

53
Q

What is the appropriate solution to soak pH meters for protein?

A

1% pepsin/0.1 M HCl for 15 minutes

54
Q

What is the appropriate solution to soak pH meters for inorganic deposits?

A

0.1 EDTA for 15 minutes

55
Q

What is the appropriate solution to soak pH meters for grease?

A

Detergent or ethanol

MEDL 200 (4 decks)

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