LABORATORY ACTIVITY 4 Flashcards
The ability to measure very small amounts, [?], of liquid chemicals or reagents is a fundamental skill needed in the biotechnology or research lab.
microliters (ul)
Scientists use a device called a [?] to measure these very small volumes with accuracy.
micropipette
This activity introduces the technique of [?]. Remember, as with all [?], this new skill will require practice and determination. Be sure to operate the [?] slowly and carefully.
micropipetting
fine motor spills
micropipette
Pick out a (?) from the rack and bring it to your bench, study it carefully and identify the parts. Draw what you see and include your illustration as part of your output.
micropipette
There are several sizes of (?) used in the molecular lab. Today, you will be using the (?).
micropipettes
P-1000, P-200, P-20 and P-20
P-1000 measures volumes between (?)
100-1000 ul
P-200 measures volumes between (?)
20-200 ul
P-20 measures volumes in the (?) range
2-20 ul
P-2 measures volumes ?
2-0.2 ul
It is important to always pick the correct (?) for the volume to be measured accurately then set the pipette to the indicated amount
micropipette
- 1.5 uL
P-2
- 160 uL
P - 200
- 700 uL
P - 1000
- 25 uL
P - 200
- 15 uL
P -20
6, 348 uL
P - 1000
- 6 uL
P-20
- 100 uL
P -1000
- 0.4 uL
P- 2
- 10 uL
P -20
Procedure (?)
Thermo Fisher Scientific
1.(?) the pipette tip: Aspirate and fully expel an amount of the liquid at least (?) before aspirating for delivery. Failure to pre-wet the tip increases evaporation within the tip air space, which can cause significantly (?) . Pre-wetting increases the humidity within the tip, thus reducing (?).
Pre-wet
three times
lower delivery volumes
evaporation
- Allow liquids and equipment to equilibrate to (?) prior to pipetting.
ambient temperature
- Examine the pipette tip for (?). Before dispensing, carefully remove (?) from the outside of the tip by touching off the side of the reservoir.
droplets
droplets
- Press the plunger to the (?), immerse the tip into the liquid, and aspirate by releasing the plunger. Remove the pipette from the liquid and press the plunger to the (?) to dispense the entire contents.
first stop
second stop
- Pause consistently. After aspirating, and before removing the tip from the liquid, pause for (?).
one second
- When aspirating liquid, hold the pipette (?) and pull the pipette straight out from the center of the reservoir.
vertically
- Hold the pipette (?) and utilize the finger rest. Remember to retum the pipette to the pipette (?) between deliveries. Avoid handling pipette tips or reservoirs with (?).
loosely
stand
bare hands
- Use the correct (?).
immersion depth
Pipette hold vertically, tip immersed about [?] into the liquid.
1 cm; 3cm
Pipette held at a 30-40 degree angle, tip immersed about [?] into the liquid.
3-4 cm
- Use consistent ?
plunger force and speed
- Repeat this process for the remaining (?).
volumes
- Be sure to watch your groupmates to provide (?) with their technique.
feedback and help
a. 345 mL =.
345000 uL
b. 0.54 mL =
540 uL
C. 5.2 L=
5,200 mL
The volume of air displaced corresponds to the selected aspiration volume
Air displacement pipettes
The piston is within the loaded tip and direct contact with the sample
Positive displacement pipettes
Easy and quick replacement of pipette tips
Air displacement pipettes
Reduced risk of contamination
Air displacement pipettes
Suitable for problematic solutions; viscous, volatile, high density or foaming
Positive displacement pipettes
Pipetting of problematic solutions; viscous, volatile, high density or foaming
Air displacement pipettes
Replacing the tip is expensive and time consuming
Positive displacement pipettes
- The pipette should be checked at the(?) for dust and dirt on the outside surfaces of the pipette.
beginning of each day
- Particular attention should be paid to the (?). No other solvents except (?) should be used to clean the pipette.
tip cone
70 % ethanol
- Push and release the knob slowly at all times particularly when working with(?) . Never allow the knob to (?).
high viscosity liquids
snap back
- Make sure that the (?) is firmly attached to the (?). Check for foreign particles in the tip.
tip
tip cone
- Before you begin your actual pipetting work, fill and empty the tip (?) with the solution that you will be pipetting.
2-3 times
- Hold the pipette in an (?) while aspirating liquid. The finger rest should rest on your (?). Make sure that the tips, pipette and solution are at the same temperature.
upright position
index finger
Aspirate and fully expel an amount of the liquid at least (?) before aspirating for delivery.
three times
Failure to pre-wet the tip increases (?) within the tip air space, which can cause significantly lower (?).
evaporation
delivery volumes
Pre-wetting increases the (?) within the tip, thus reducing (?).
humidity
evaporation
Before dispensing, carefully remove (?) from the outside of the tip by touching off the side of the reservoir, being sure to stay clear of the tip opening to avoid wicking liquid out of the tip.
droplets
After dispensing, and before releasing the plunger, deliver any (?) remaining in the tip by touching the tip to the side of the container.
residual liquid
(?) will help draw the remaining liquid out of the tip.
Surface tension
After aspirating, and before removing the tip from the liquid, pause for (?). Make this pause as consistent as possible.
one second
Liquid continues to flow into the (?) for a short time after the plunger stops. At the same time, evaporation within the (?) is occurring.
tip
tip
(?) consistently balances these two effects and ensures correct aspiration.
Pausing
When aspirating liquid, hold the pipette (?) and pull the pipette straight out from the center of the reservoir.
vertically
This technique is especially important when pipetting small volumes (?).
Remove the pipette straight from the vessel
less than 50μL
Holding the pipette at an angle as it is removed from the liquid alters the ?.
aspirated volume
Hold the pipette (?) and utilize the finger rest.
loosely
Remember to return the pipette to the pipette (?) between deliveries.
stand
Avoid handling pipette tips or reservoirs with ?.
bare hands
(?) transferred during handling disturbs (?), which leads to variations in delivered volume.
Body heat
temperature equilibrium
Effects of immersing the tip (?) and (?) the pipette are greater with small sample volumes, e.g., using (?) pipette.
too deeply
tilting
1-10 ul
Allow liquids and equipment to equilibrate to (?) prior to pipetting.
ambient temperature
The volume of liquid delivered by air displacement pipettes varies with relative (?) of the liquid – both of which are temperature-dependent.
humidity and vapor pressure
Working at a (?) minimizes variation of pipetted volume.
constant temperature
Temperature differences cause (?) in the air space.
thermal expansion and shrinking
After temperature equilibrium, the influencing factor is ?.
liquid density
Cold liquid is (?) and hot liquid is (?) compared to room temperature liquids.
more dense
less dense
? are designed to work with their matching pipettes.
System tips
Mismatched tips and pipettes can result in ?.
inaccuracy, imprecision, or both
Quality system tips provide an (?) , are made of (?), and are free of (?).
airtight seal
superior materials
molding defects
A (?) will | dispense all liquid in a tip.
smooth inner wall
A (?) will hang up liquid in a tip, resulting in poor
rough inner wall
(?) can hang up liquid, resulting in poor
Flash at the orifice
They also ensure dependable (?).
liquid delivery
Tip incorrectly attached
:
Defect: Leakage
Solution: Attach firmly
Foreign particlesbetween tip and tip cone
Defect: Leakage
Solution: Clean tip cones attach new tips
Foreign particles between the piston, the O-ring and the cylinder
Defect: Leakage
Solution: Clean and grease O-ring and cylinder.
Insufficient amount of grease on cylinder and O-ring
Defect: Leakage
Solution: Grease accordingly
O-ring damaged Incorrect operation
Defect: Inaccurate dispensing
Solution: Change the O-ring
Follow instructions carefully
Attach firmly
Recalibrate according to instructions
Recalibrate with the liquids in question
Tip incorrectly attached
Defect: Inaccurate dispensing
Solution:
Calibration altered: caused by misuse, for example
Defect: Inaccurate dispensing
Solution:
High viscosity liquids may require recalibration
Defect: Inaccurate dispensing with certain liquids
Solution:
Unsuitable calibration
Defect: Inaccurate dispensing with certain liquids
Solution:
Defect:
Solution:
Defect:
Solution:
