Pipetting Technique and Centrifugation (P) Flashcards
What is pipetting technique?
A technique used to transfer aliquot of liquid sample from one container to another
What are the different types of pipettes?
1) According to Design
2) According to Drainage
3) According to Type
What are the different types of pipettes under according to design type of pipette?
1) To contain (TC)
2) To deliver (TD)
What is TC?
TC pipette holds or contains a particular volume but does not dispense that exact volume
What is TD?
TD will dispense the volume indicated
What type of pipette under according to design type is more common?
TD pipettes are more common than TC pipettes
What are the different types of pipettes under according to drainage type of pipette?
1) Blow-out
2) Self-draining
What is the characteristic of blow-out pipette?
Blow-out pipette has frosted bands or two continuous rings or etched rings at the top
What should be done when blow-out pipette is used?
The last drop is fully expelled into the receiving vessel
What should be used when expelling the last drop of liquid or reagent in blow-out pipette?
Aspirator bulb
What is self-draining pipette?
The contents of self-draining pipette are drained by gravity
What are the types of pipette under according to type pipettes?
Measuring or Graduated
What are the functions of measuring or graduated pipettes?
Used to transfer reagents and make dilutions
Used to dispense several volumes
What are the 3 types of measuring or graduated pipettes?
1) Serologic
2) Mohr
3) Micropipette
What are the characteristics of serologic pipette?
1) The graduations are located after the tip of the pipette
2) It is a blow-out pipette
What is a Mohr pipette?
1) The graduations are located before the tip of the pipette
2) It is a self-draining pipette
What is the volume capacity of micropipette?
< 1 mL
Can micropipettes be designed as serologic or Mohr pipette?
Micropipettes can be designed as either serologic or Mohr pipette
What are micropipettes?
Micropipettes are the small version of measuring pipettes
Is the total volume of a pipette indicated in the pipette (measuring or graduated) itself?
Yes, including the dilutions or major divisions where the specific pipette can be used
What are the 4 types of transfer pipettes according to type?
1) Volumetric
2) Ostwald-Folin
3) Pasteur pipettes
4) Automatic pipettes
What is the general term for all types of pipettes under according to type?
Transfer pipette
What is a transfer pipette?
It dispenses one volume without further subdivisions
What are the characteristics of volumetric pipette?
1) It carries aqueous solutions
2) Most accurate and precise
3) Self-draining
What are the characteristics of Ostwald-Folin pipette?
1) It carries viscous fluid
2) Blow-out
What are Pasteur pipettes?
It is the disposable type of pipette
When are automatic pipettes used?
Automatic pipettes are routinely used in the CC lab
What are the 2 types of automatic pipettors?
1) Micropipettes
2) Macropipettes
What is the volume capacity of micropipettes?
< 1 mL
What is the volume capacity of macropipettes?
1 mL >
What are the materials needed for (serological pipetting) pipetting?
1) Serological pipette
2) Aspirator bulb
3) Automatic pipettors
4) Beaker (50 mL)
5) Distilled H2O
What is the procedure of using serologic pipettes?
1) Rinse the pipette twice (2x) with distilled water.
2) The pipet should be held upright. Immerse the tip in the liquid to be transferred without touching the vessel walls.
3) Use an aspirator/pipet bulb, apply a slight suction until the liquid enters the pipet.
4) When the MENISCUS is brought above the desired graduation line (ASPIRATION), stop the suction.
5) Quickly place your dry index finger over the upper opening of the pipette to control the flow of liquid.
6) Wipe with a tissue of any adhering liquid.
7) Prepare your receiving vessel/beaker.
8) Adjust the contents to desired volume by gently releasing the finger
What are the parts of an automatic pipettor?
1) Push button (or plunger)
2) Ergonomic grip cover
3) Tip ejector
4) Digital display
5) Tip ejector collar
6) Tip cone
How to use an automatic pipettor?
1) Adjust to the desired volume.
2) Get a pipette tip from a pipette tip rack.
3) Hold the pipette in a vertical position.
4) Depress the plunger to the FIRST STOP.
5) Immerse the pipette tip (HALF) into the liquid.
6) Release the plunger to aspirate liquid sample.
7) Depress the plunger all the way to the SECOND STOP to transfer it to the receiving vessel.
8) Allow the plunger to move up to the rest position.
9) Eject the tip (ejector tip)
What are the considerations that should be observed for proper care of automatic pipettes?
1) Store pipettes vertically to avoid contamination
2) Store pipettes dialed to the lowest volume setting
3) Store away from heat and moisture
4) Pipette tips should be removed prior to storage
5) Calibration should be done (3 - 6 mos according to CLSI)
6) When cleaning pipettes with bleach solution, do not saturate as fluid can make its way to the piston and cause corrosion
What is centrifugation?
It is the process in which centrifugal force is used to separate solid matter (sediment) from a liquid suspension
What is the expression (or unit) for the speed in centrifugation?
It is expressed in revolutions per minute (RPM)
What are the 2 types of speed in centrifugation?
1) Low-speed
2) High-speed
What is the speed under low-speed in centrifugation?
0 - 7,500 RPM
What is the speed under high-speed in centrifugation?
20,000 RPM >
What are the parts of a digital centrifuge?
1) Automatically electric (or eletric?) lid lock
2) Rotor
- > 4 x 800 mL swing rotor
3) Model
4) Stop
5) Start
6) Logo
7) Program
- > 10 kinds (depending on your choice)
8) Deceleration
9) Acceleration
10) Speed
What should be done to acquire proper counterbalancing?
1) Ensure all sample tubes are evenly filled.
2) For each tube inserted in the rotor, add a tube of equal weight directly opposite it. This will ensure the center of gravity remains in the center of the rotor.
3) Make sure to take note of the positioning in the rotor
How to operate a centrifuge (bench-top model)?
1) The work surface must be level and firm
2) Connect to a power supply
3) Counterbalance the tubes in the rotor
4) Adjust the speed
5) Set the timer
6) Click start
7) Wait for the centrifuge to reach its full stop (beep sound)
8) Open the lid. Use goggles or shields
9) Take out the sample tubes
10) Close the lid and perform cleaning of the centrifuge
What are the considerations that should be done when it comes to care and maintenance of centrifuge?
1) Ensure all users are aware of how to properly operate the centrifuge
2) Inspect critical components, and look for signs of wear including scratches, or effects of chemical exposure on the rotor
3) Pay close attention to noise, vibration, shaking, or grinding, and stop the unit immediately if this occurs
4) Regularly clean the centrifuge with neutral cleaning solutions (alcohol or alcohol-based disinfectant) applied with a soft cloth to rotors and accessories
