[1S] UNIT 3: Pipetting Flashcards
➢ glass or plastic tubes
➢ open at both ends
➢ transfer specific amounts of liquid from one
container to another.
➢ usually used for volumes between .01 and 10
milliliters.
Pipettes
TYPE 1: ACCORDING TO DESIGN
Water is used for calibration. Allow liquid to flow by gravity, don’t blow. For non-viscous liquids
To deliver
TYPE 1: ACCORDING TO DESIGN
Hg is used for calibration. Exact volume is delivered by repeated filling and emptying with the diluents. For viscous liquids
To contain
TYPE 2: ACCORDING TO DRAINAGE CHARACTERISTIC
• similar to TD pipet
• Last drop is blown out to get the exact volume
• An etched or frosted ring indicate calibration
To blow out pipet
TYPE 2: ACCORDING TO DRAINAGE CHARACTERISTIC
contents are allowed to drain by gravity
Self draining
TYPE 3: MEASURING / GRADUATED PIPETS
has calibration marks to the tip and is generally a blow-out pipet
Serologic
• capable of dispensing different volumes
• Uniform graduation along its length
• Deliver fractional quantity of liquid
• Used for reagent measurements
Measuring or Graduated pipets
TYPE 3: MEASURING / GRADUATED PIPETS
does not have graduations to the tip, self draining
Mohr
TYPE 3: MEASURING / GRADUATED PIPETS
may either be a serological or mohr. Calibrated either TC or TD. With total holding volume of less than 1 ml.
Micropipet
Printed on the neck of the pipette are the specifications that indicate:
- maximum volume of liquid that can be transferred
- size of the divisions on the pipette
- temperature at which calibrations were made
- if the pipette is a “to deliver”(TD) or “to contain”(TC)
pipette.
designed to dispense one volume
Transfer Pipets
TYPE 3.B: TRANSFER PIPETS
• has a cylindrical bulb located midway between the mouth and the tip.
• calibrated TD a fixed volume of liquid
• allowed to drain only
Volumetric
TYPE 3.B: TRANSFER PIPETS
• used for accurate measurement & other non-viscous fluids
• has the greatest accuracy & precision
• deliver a single specific volume of liquid, usually
between 1 and 10 ml.
Volumetric
TYPE 3.B: TRANSFER PIPETS
• For accurate measurements
• Deliver one volume only
Volumetric
SPECIFICATIONS ON A VOLUMETRIC PIPETTE
T/F: 1. When emptying a volumetric pipette, the liquid is not allowed to drain out. It is forced out.
F; When emptying a volumetric pipette, the liquid is allowed to drain out. It is NOT forced out.
SPECIFICATIONS ON A VOLUMETRIC PIPETTE
T/F: 2. After it is emptied, the small amount of liquid which remains in the tip should not be blown out.
T
SPECIFICATIONS ON A VOLUMETRIC PIPETTE
T/F: Volumetric pipettes are NOT blow-out pipettes
T
TYPE 3.B: TRANSFER PIPETS
• bulb is located closer to the delivery tip
• with an etched ring/blow-out pipet
• used to measure viscous fluid
Ostwald-Folin Pipet
TYPE 3.B: TRANSFER PIPETS
have no calibration marks and are used to transfer solutions or biologic fluids without consideration of a specific volume.
Pasteur pipet
TYPE 3.B: TRANSFER PIPETS
most routinely used.
Advantages: safety, stability, ease of use, increased
precision, saves time, less cleaning is required.
Automatic pipets
AUTOMATIC PIPETS
- associated with 1 volume
- ranges from 1ul to 1000 ml
- fixed
- variable
AUTOMATIC PIPETS
has a pipetting capability of less than 1 ml
Micropipet
AUTOMATIC PIPETS
dispenses greater than 1 ml
Automatic macropipet
GENERAL TYPES OF AUTOMATIC PIPETS
relies on a piston for suction creation to draw the sample into a disposable tip that must be changed after each use.
Air Displacement
