Micropipetter Tutorial

Fawks

Informations

• Publié par: Nezog
• Nombre de lectures: 19
• Langue: English

Extrait

Appendix B:
Micropipetter Tutorial
How Not to Break A Micropipetter!Introduction
Th ese machines are EXPENSIVE. Be sure to follow these Micropipetters are continuously adjustable pipettes which
simple rules:are used to draw up and deliver specifi ed volumes. Th e
1. Do NOT dial a pipetter below 0volume is determined by adjusting the volume adjustment
2. Do NOT dial a pipetter above their maximum valueknob. Th e volume, in microliters, is displayed in the volume
3. Do NOT drop a pipetterindicator. Th e fi rst section describes the parts and general use
4. Do NOT submerge the shaft of a pipetter in liquidof a micropipetter. Th e second section describes how to use a
5. Do NOT pound the pipetter into a tip micropipetter and includes an exercise. Refer to the micropi-
6. DO think about what you’re doing and DO use common petter diagram on the next page as you read this tutorial.
sense!
Metric conversions: small volumes
B. Micopipetter Instructions
Th e two most prevalent units of liquid measurement in
Your instructor will demonstrate the proper use of micropi-molecular biology are the milliliter (mL) and the microliter
petters and sterile technique. Although the instructions below (μL).
apply specifi cally to the P-20, they are also applicable to the
P-200 and P-1000. Refer to Figure 1 on the next page.
1 mL = 0.001 liter or 1/1,000 liter 1,000 mL = 1 liter
1 μL = 0.000001 liter or 1/1,000,000 liter 1,000,000 μL = 1 liter
1 μL = 0.001 mL or 1/1000 mL 1,000 μL = 1 mL 1. Hold the micropipetter towards you so that you can see
the Digital Volume Indicator. Th e number you see is the
A. Micopipetters: Getting Started
volume of fl uid, in uL, that will be dispensed. To adjust
the volume, gently rotate the Volume Adjustment Knob Th ere are three common sizes of micropipetters, which
until the correct volume is displayed. Rotate clockwise cover the volume range of 1uL to 1,000uL. Th e largest, the
to decrease, counterclockwise to increase. Never force P-1000, has a plunger button labeled P-1000. Th e other two
the adjustment. Approach the desired volume by dialing have plunger buttons labeled P-20 and P-200. All three have
downward from a larger volume.
a window (digital volume indicator) with numbers showing
the volume being withdrawn or dispensed.
2. Use a tip at all times.
Th e P-1000 is used for volumes ranging from 200-1000uL
and require the use of the larger plastic pipette tips. Th e P-20 3. B efore using the micropipetter, get used to feel of the fi rst
and P-200 are designed for vom 1-20uL and second “points of resistance” of the micropipetter.
(P-20) or from 20-200uL (P-200). Th ey require the use of Depressing the plunger to the fi rst “point of resistance”
the smaller pipette tips. allows the desired volume of your solution to be drawn
into (or dispensed from) the tip. Depressing the plunger
to the second “point of resistance” introduces an additional You must know how to correctly use the micropipetters. Th is
volume of air, which blows out any remaining solution. includes correctly using sterile technique to add the tips and
Th is will become clear when you actually practice with the correctly disposing of the tips.
micropipetter.
B-1Micropipetter Tutorial
Plunger button 4. T o withdraw a sample:
a. Th e micropipetter must have a tip. Open the tube of
Tip ejector button sample solution and hold it by the body, not the lid,
Volume
fi rmly between your thumb and forefi nger. It helps to Adjustment
Knobhave the tube near eye level.
b. D epress the plunger to the fi rst “point of resistance”
Digital Volume and hold it.
Indicator
c. While holding the micr opipetter in a vertical position,
immerse the tip into the sample and withdraw fl uid
by gradually releasing the plunger. DO NOT LET IT
SNAP UP. Wait 1-2 seconds to ensure that the full
volume of sample is drawn into the tip. Watch! Slide
the tip along the inside wall of the tube to dislodge any
excess droplets adhering to the outside of the tip. Never
set down a micropipetter with a fi lled tip.
5. To dispense a sample:
a. Touch the pipette against the inside wall of the receiving Tip ejector
vessel. Th e capillary action helps to dispense the fl uid.
b. Slowly depress the plunger to the fi rst “point of resis-
tance” and wait 1-2 seconds.
c. D epress the plunger to the second “point of resistance”
Figure 1(while still holding the tip against the side of the tube).
Micropipetter diagramDisposable Tip Th is will expel any residual liquid.
d. K eeping the plunger fully depressed, withdraw the
micropipetter by carefully sliding the tip out along the
wall of the vessel.
6. To discard the tip:
D iscard the tip into the beaker labeled “Waste tips and
tubes” found at your bench. To do this, depress the ejector
button while holding the tips over the beaker. Use a fresh
tip for each sample unless told otherwise.
** Practice: Adjust the micropipetter to 4uL (or 400uL or
40ul if you are using a P-1000 or P-200 respectively) and
practice pipetting dye into an empty centrifuge tube.
B-2