www.mt.com/raininFor more information

Improve Your Research Results Technique directly affects the success and repeatability of your experiments. Rainin’s Good Pipetting Practice™ techniques will improve your pipetting performance.

5%

0%

Instrument / Environment

Immersing the tip too far can cause more liquid to be aspirated. Conversely, if the tip is not immersed far enough, air can be aspirated. Both result in inaccurate volume. Correct tip immersion depth can improve accuracy by up to 5%, so use the recommended depths shown here. (>2000 µl, use 6-10 mm depth)

Consistent pipette rhythm and speed

Good aspiration Tip that aspirated air

Maintaining consistent pipetting rhythm and speed will produce optimal, more repeatable results. Fast or “jerky” aspiration can cause splashing, aerosols, shaft contamination and loss of sample volume. With consistent rhythm and speed you can achieve up to 5% accuracy improvement.

Keep the immersion angle vertical or within 20° of vertical – angles greater than that can produce inaccurate measurements. For micro-volume pipettes, keeping the angle close to vertical can improve accuracy by up to 2.5%.

Correct angle Incorrect angle

Dispensing onto liquid surface

Good dispensing technique can improve accuracy by up to 1%. When dispensing sample, make sure the tip end touches the vessel wall, which will prevent sample from remaining in the tip. After dispensing, sliding the tip end up the vessel wall will release any liquid remaining on the orifice.

Two other techniques: dispensing into the liquid or onto the liquid surface. When dispensing directly into or onto liquid, use reverse-mode pipetting to avoid picking up sample after dispensing.

Dispensing against vessel wall

Dispensing into liquid

An ideal temperature for pipetting is 21.5°C±1°C – the same as is used for calibration. Avoid drafty or sunlit areas that could cause large or sudden temperature changes that compromise aspiration accuracy. Pipetting at a constant temperature can improve results by as much as 5%.

Improve accuracy and precision by up to 1% by aspirat-ing and dispensing samples within the range of 35% to 100% of a tip’s nominal volume.

Also, avoid setting a pipette’s volume to less than 10% of its maximum – instead, switch to a smaller volume pipette for smaller volumes.

When changing the volume from a higher to a lower setting, dial down to the desired volume setting. However, when changing the volume from a lower to a higher setting, turn the selector wheel about 1/3 turn above the desired volume setting, then slowly back down until you reach your desired setting. This avoids mechanical backlash and results in greater accuracy.

Over long periods of pipetting, heat from your hand can warm the pipette, causing the air space inside to expand and produce inaccurate results.

Avoid the effects of hand-warming by using a quality pipette made from PVDF polymers. In addition, between pipetting cycles, replace the pipette on its stand instead of holding it your hand.

© 9/2011 Rainin and Mettler-Toledo AG. GPP and Good Pipetting Practice are trademarks of Rainin and Mettler Toledo AG.Printed in U.S.A.Marketing Rainin

Tip immersion depth

Consistent micrometer setting

Pre-rinse the tipPre-rinsing the tip two or three times forms a liquid film on the inside of the tip that can increase accuracy by up to 0.2%. Pre-rinsing helps neutralize capillary effects in micro-volume pipettes and, for large-volume tips, equalizes the air temperature inside the tip with the temperature of the sample.

Good ergonomics

Hand-warming effects

Improve performance by taking it easy on your hands. It’s a fact that hand fatigue leads to errors, especially after a large number of samples have been dispensed.

What is good ergonomics? Using good posture and pipettes with finger-hooks that allow you to relax your grip at regular intervals. Switching hands periodically will also help reduce fatigue and increase your productivity.

Rainin pioneered many of the ergonomic features found in modern pipettes. Our light spring forces and patented LTS LiteTouch tip ejection system are considered by many life scientists to be essential safety equipment.

5%

5%

5%

1%

0.5%

1%

0.2%

1%

2.5%

Pipetting Techniques

1-10 µl: 1-2 mm 10-200 µl: 2-3 mm 200-2000 µl: 3-6 mm

Vertical immersion angle

Press and release plunger 2 or 3 times

Volume vs. range

Constant temperature

100%

35%

10%

Consistent sample dispensing

OP

OP