MIDTERM LAB: PIPETTING Flashcards
is filled to a particular graduation, and delivers less the volume
TO CONTAIN
will take slightly more than actual volume, but deliver the actual amount
TO DELIVER
TYPES OF MICROPIPETTES: BASED ON WORKING PRINCIPLE
Consists of PISTON which aspirates
& dispenses liquid samples as the
air pocket moves up & down,
respectively
A disposable pipette tip is used
Recommended for AQUEOUS
SAMPLES
AIR DISPLACEMENT MICROPIPETTE
TYPES OF MICROPIPETTES: BASED ON WORKING PRINCIPLE
Piston comes in direct contact of
the sample
Microsyringe composed of
capillary & a piston is used
Recommended for PROBLEM
SAMPLES
POSITIVE DISPLACEMENT MICROPIPETTE
- Aqueous
- Water, sucrose, Tris,
buffers with pH of 7
RECOMMENDED PIPETTES?
AIR DISPLACEMENT
- Biological
- DNA, RNA, proteins
AIR DISPLACEMENT WITH FILTER TOPS
- Viscous
- Glycerol, surfactants, oil
POSITIVE DISPLACEMENT
- Volatile
- Ethanol, hexane,
formaldehyde
POSITIVE DISPLACEMENT
-Hazardous
- Radioactive isotopes, blood, infectious, bacteria or viruses
POSITIVE DISPLACEMENT
Corrosive Acids
- such as hydrochloric acid or sulfuric acid, bases such as ammonium hydroxide salts such as sodium chloride
POSITIVE - DISPLACEMENT
OPERATING MECHANISM
Operate manually based on a
piston – shaft spring mechanism
MECHANICAL MICROPIPETTE
Mostly automated
Aspirating & dispensing of liquid is
performed by the one – touch
buttons instead of manual plunger
Piston is motor – driven
ELECTRONIC MICROPIPETTE
VARIANTS OF MULTI CHANNEL MICROPIPETTE
8, 12, 16 CHANNEL MICROPIPETTE
NUMBER OF CHANNELS
Reduce the workload of a single
channel micropipette when
working with large volumes of
sample
MULTI CHANNEL MICROPIPETTE
VOLUME/CAPACITY
Volume of liquid to be aspirated/dispensed REMAINS FIXED
Used when the same volume of liquid is to be dispensed multiple times
FIXED VOLUME MICROPIPETTE
Has specific minimum and maximum volume range
Volume of the liquid to be aspirated/dispensed can be adjusted (within the instrument’s volume range) depending upon the requirement of the user
VARIABLE VOLUME MICROPIPETTE
Test tubes and centrifuge tubes are used with ______________________for sample preparations such as qPCR
templates
single channel micropipettes
LONG TEST TUBES, also assays tubes, are used with ______________ and __________- with plastic or glass pipettes; these devices are specially designed to reach the bottom of these tubes
positive – displacement pipettes; pipette fillers
REAGENT RESERVOIRS are ideal for dispensing reagents, especially with ____________
multichannel pipettes
96 – well and 384 – well microplates, as
well as 8 – well strips, are commonly used with _______________ for application like ELISA, but also with single channel pipettes.
air – displacement multichannel pipettes
MICROPIPETTE STRUCTURE
- PLUNGER (PUSH BUTTON)/VOLUME ADJUSTMENT WHEEL (KNOB)
- TIP EJECTOR
- VOLUMES WINDOW/VOLUMETER DISPLAY
- SHAFT
- DISPOSABLE TIP
A ______ angle & ______ immersion depth guarantee the most accurate pipetting result
vertical angle; low immersion depth
TO DISPENSE SAMPLE:
Place the pipette tip at angle _______
against the inside wall of the receiving
vessel
(10-45°)
PIPETTING TECHNIQUES
Aqueous liquids: buffers, diluted acids/alkali
FORWARD
PIPETTING TECHNIQUES
Highly viscous/foaming tendencies
REVERSE
WHEN TO CHANGE A TIP?
When transferring a single sample of DIFFERENT LIQUIDS, select a new pipette tip for each new liquid.
Leftover portion of sample “A” can mi with the net sample “B” & may cause a false test result
SAMPLE CARRY OVER
Store in a clean, cool & dry place ___________(from -4 °F to 120 °F) with relative humidity between _________
(- 20 °C to 50 °C); 5% & 95%;
CALIBRATIONS IS DONE EVERY _______
6 MONTHS
