How to Use BRAND^® Pipettes

Section Overview

• Handling of Pipettes
• Working With Pipetting Aids
• Related Materials

Pipettes are volumetric instruments for measuring volumes of liquid and are generally calibrated 'to deliver'. During the manufacturing process, they are individually volumetrically calibrated and provided with one or more calibration marks.

We distinguish between bulb and graduated pipettes (calibrated to deliver, TD, Ex) and disposable micropipettes up to 200 μL (calibrated to contain, TC, In).

Bulb pipettes

• Calibration:
  - Class AS: 'Ex + 5 s'
  - Class B: 'Ex'
• Generally higher measurement accuracy than graduated pipettes
• Bulb pipette models:
  The most important model is the bulb pipette with 1 mark (total delivery). Less common is the model with 2 marks (partial delivery).
  Bulb pipettes are also called single volume pipettes.

Graduated pipettes

• Calibration:
  - Class AS: 'Ex + 5 s'
  - Class B: 'Ex'
• Scaling permits the reading of partial volumes
• Types of graduated pipettes:
  - Type 2 – nominal volume at top, total delivery also for partial volumes
  - Type 1 – nominal volume at bottom, partial delivery for all volumes
  - Type 3 – nominal volume at bottom, total delivery only for the nominal volume

Graduated pipette, type 2, nominal volume at the top

Capillary pipettes
e.g., BLAUBRAND^® intraMark

Calibrated to contain (TC, In)

One ring mark

Volume limited by one end and the ring mark

Capillary pipettes
e.g., BLAUBRAND^® intraEnd

Calibrated to contain (TC, In)

No ring mark

Volume limited by both ends (end-to-end capillaries)

Handling of pipettes

Pipettes calibrated 'to deliver' ('TD, Ex')

Proper pipetting with bulb pipettes with 1 mark (here: nominal volume 25 mL) and graduated pipettes type 2, class AS (here: partial volume 3 mL) Utility: pipetting aid (page 18)

Filling:

1. Fill the pipette with a pipetting aid to approx. 5 mm above the selected graduation mark.
2. Remove any liquid remaining on the outside of the tip of the pipette with a tissue.
3. Set the meniscus.
4. Wipe off any drop of liquid adhering to the tip.

Delivering:

1. Hold the pipette vertically. Deliver the liquid with the tip of the pipette in contact with the inner surface of the inclined receiving vessel.
2. When the meniscus comes to a rest in the tip, the waiting time of 5 s begins (class AS only).
3. After the waiting time, draw the pipette tip upwards along the inner wall through a distance of about 10 mm to remove residual liquid.

Note: The residual liquid still left in the tip has already been accounted for during calibration and must not be discharged into the vessel, such as by blowing out.

Type 1 and type 3

When using type 1 or type 3 graduated pipettes (zero point at top), the meniscus must

1. first be set at the zero point and then the liquid be run out to slightly above the desired partial volume.
2. After a waiting time of 5 s, the meniscus  should be set a second time.

Working with type 2 graduated pipettes is significantly quicker and simpler. With type 1 and type 3 pipettes there is a risk that with the always necessary second meniscus setting too much liquid is released, and that the sample needs to be prepared again (as also with bulb pipettes that have 2 marks).

Pipettes calibrated 'to contain' (TC, In)

Correct pipetting with capillary pipettes

Utility: pipetting aid (page 18)

Capillary pipettes are pipettes with a very narrow internal diameter. They are filled either with a pipetting aid, or automatically by capillary action. After emptying, the capillary pipette must be rinsed repeatedly with the diluting medium.

Filling

• Aspirate liquid accurately to the desired mark.
• Hold the pipette horizontally and carefully wipe off with a tissue.

Delivering

• To empty capillaries blow out the liquid with a pipetting aid, and rinse two to three times with the diluting medium (required due to calibration 'to contain').
• End-to-end capillaries are often placed directly in the dilution solution and washed out by shaking.

Pipette holder with end-to-end capillaries

Working with pipetting aids

Pipetting using the mouth or with a tube and mouthpiece is not allowed. A pipetting aid should always be used for this. This significantly decreases the risk of infection or injury.

Pipetting aids are indispensable for working with pipettes.

Types of pipetting aids:

• motorized pipetting aids
• manual pipetting aids

Motorized pipetting aids

Motorized pipetting aids are ideal for pipetting longer series (e.g., for cell cultures). e.g., accu-jet^® pro by BRAND^®

The variable motor speed control and a special valve system enable sensitive operation with pipettes from 0.1 to 200 mL.

An integrated check valve in connection with a membrane filter effectively protects against penetrating liquids. To protect against corrosion, an active pressure compensation diverts vapors outside.

Handling

Pipetting is controlled through two large function buttons.

• Filling

To fill the pipette, press the upper button. Intake rate is continuously variable by trigger pressure.

• Delivery

Discharge rate is continuously variable by trigger pressure.

Choose Free delivery or Power delivery

Dispensing liquid: free delivery or power delivery?

The choice of delivery modes is determined by the application. In the analytical laboratory, the 'free delivery' mode is often preferred in order to obtain the required volumetric accuracy. To achieve the accuracy indicated on the pipettes, it is necessary to allow the liquid to run off freely, and to observe the delivery and waiting times. In microbiology, however, volumetric accuracy is less significant. Here, the uniform and rapid delivery of nutrient solutions, etc. is of primary importance. Therefore, the 'power delivery' mode is usually preferred in this field.

 Manual pipetting aids

Manual pipetting aids are used when pipetting a short series, primarily in chemical laboratories.

e.g., macro pipette controller by BRAND^®

The macro is compatible with the full range of bulb and graduated pipettes from 0.1 to 200 ml. The special valve system allows easy meniscus adjustment. A hydrophobic membrane filter protects the system against penetrating liquid.

Handling

Create negative pressure: Squeeie bellow.

Filling: Move pipetting leverupward. The farther up the lever is pressed, the faster the pipett e will fill.

Adjust meniscus/ dispensing by 'free delivery': Press pipetting leverslightly downward. The meniscus falls- release the lever, the meniscus stops. To dra in the pip ett e, press the lever all the way down. Tocomply with class A accuracy, do not blow out the residual liquidI

Blow out: When pipetting viscous media with 'free delivery', the pipette tip frequently does not empty completely. In these cases, blow out any remaining residues by pressing on the rubber bulb of the macro pipette controller.

Pipette filler

The classic standard pipetting aid for bulb and graduated pipettes.

Handling

1. Insert top of pipette
2. Press 'A' and squeeze the ball (create negative pressure)
3. Press 'S' to aspirate liquid just above the desired mark
4. Press 'E' to discharge liquid to the desired mark, or to drain the pipette

Blow out

• To blow out viscous media, the side opening must be closed and the small ball compressed.

Attention!

The pipette filler should not be stored in the primed state, so that no liquid will be taken up!

Special pipetting aids have been developed for these pipettes. They are used in the medical field with capillary pipettes, blood diluting pipettes and blood sugar pipettes up to a max of 1 mL.

Handling

Filling/ Delivery: Turn the thumb wheel to take in anddeliver liquid. Pipettes cali brated to cont ain (TC,In) should be washed mult iple times by filling and emptying with dilution solution.

Dispensing by 'free delivery': To deliver liquid from pipet tes calibrated to deliver (TO, Ex), press the air release button (observing the w aiting tim e if necessary).

Eject: The large ejector key allows ejectionof used pipettes without hand contact.

e.g., micro-classic pipette controller by BRAND^®

Due to its angled design, it is especially suitable for work under a microscope in IVF laboratories and in medical laboratories.

Handling

Attaching the pipette: Always attach the short end of the pipette, i.e. hold at the color code of th e pipette and carefully slide it into the adaptor.

Filling: Turn the thumb wheel backward until liquid reaches the desired mark.

Delivery: Pipettes calibrated 'to contain': Turn the thumb wheel forward until liquidisdelivered.Rinse thepipette at least three times with the dilution solution. Pipettes calibrated 'to dellver': For 'free delivery' press the air release butt on unti l liquid has run out (observewaiting time if required).