[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
GENERAL TYPES OF AUTOMATIC PIPETS
operates by moving the piston in the pipet tip or barrel, much like a hypodermic syringe. Does not require different tip for each use. Requires rinsing and blotting between samples to prevent carryover.
Positive Displacement
GENERAL TYPES OF AUTOMATIC PIPETS
automatic pipets that obtain the liquid from a common reservoir and dispense it repeatedly. The dispensing pipets may be bottle –top, motorized, handheld or attached to a dilutor.
Dispensers and Dilutors
