Recommendations for pipetting liquids

Getting started

  • Check your pipette at the beginning of your working day for dust and dirt on the outside. If needed, wipe with 70 percent ethanol.
  • Check that you are using tips in agreement with the manufacturer's specification. Thermo Scientific pipettes are calibrated using Thermo Scientific pipette tips.
  • To ensure accuracy, use only high-quality tips made from contamination-free virgin polypropylene.
  • Tips are designed for single use. They should not be cleaned for reuse, as their metrological characteristics will no longer be reliable.
    • Pipette parallel samples in a similar way, e.g., pipette in the same position with the tip in the same depth, using the same speed for plunger movements.
    • Avoid turning the pipette on its side when there is liquid in the tip. Liquid might get into the interior of the pipette and contaminate the pipette.
    • Avoid contamination to or from hands by using a tip ejector for tip removal.
    • Always store pipettes in an upright position on a stand when not in use.
    Solution and / or compoundExamplesPipettePipette TipPipetting techniqueComments
    Aqueous solutionBuffers, diluted salt solutionsAir displacementStandardForward 
    Viscous solutionProtein and nucleic acid solutions, glycerol, Tween 20/40/60/80Air displacement

    Positive displacement
    Standard or wide orifice, Low Retention

    Positive displacement
    ReversePipette slowly to avoid bubble formation.
    Volatile compoundsMethanol, hexaneAir displacement

    Positive displacement

    Positive displacement
    ReversePipette rapidly to reduce the effect of evaporation. Carbon filter tips protect the integrity of the pipette by eliminating exposure to harmful vapors.
    Body fluidsWhole blood, serumAir displacementStandard or wide orifice tipHeterogeneous*Residual liquid can be found on the outer surface of the tip. Wipe the tip against the edge of the vessel to remove this liquid before dispensing.
    Nucleotide solutionsGenomic DNA, PCR productsAir displacement

    Positive displacement
    Filter/Barrier or wide orifice

    Positive displacement
    For genomic DNA wide orifice tips can be used to eliminate mechanical shearing. 
    Radioactive compounds14Carbonate,
    Air displacement

    Positive displacement

    Positive displacement
    Acids/alkalisH2SO4, HCI, NaOHAir displacementFilter/BarrierForward 
    Toxic samples Air displacement

    Positive displacement

    Positive displacement
    Forward or reverse 

    *With blood or serum reverse technique is another option. During the aspiration and dispensing, use very slow plunger movements. When aspirating, hold the tips in the liquid for a few seconds, after the plunger is in the upper position. Also, when dispensing, move plunger slowly and wait a few seconds when plunger is in the down position.

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