Where possible a forward pipette (Transfer) operation should be used to get the best accuracy and precision; however, sometimes you need to quickly distribute liquid across a plate.

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Background

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When performing a multi-dispense (Aliquot) operation there are two important things to keep in mind:

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• The first dispense (pre-dispense) will always be under
• The final dispense (post-dispense) will have less volume than expected

Due to how the mechanics of the pipette module work the initial dispense on a multi-dispense will be guarenteed to be less than the expected volume. As the i.prep gets to the final dispense this will also have less volume than expected as the errors accumulated through each dispense.

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As a result of this the first and last dispenses should always be made back to source.

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Configuring Pre and Post Dispense

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To configure the first dispense to go back to source in <flow>, select the first destination to be the same item as the source.

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To configure the final dispense to go back to source make sure your total number of destinations does not consume all of the available volume and toggle on the Return excess to source option when configuring the dispense.

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Adding an Air Gap

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To further improve multi-dispense you can add a small Air Gap volume with the Air Gap Flow Rate set to the same as the Dispense Flow Rate to aid in sheering each dispense.

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Pre-Wetting

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Certain liquid types will see better multi-dispense performance when pre-wetting the tip. Consider adding a transfer that aspirates and dispenses the full volume from and to the source before performing the multi-dispense.

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Where possible try to limit the number of multi-dispense steps performed with a single tip before exchanging.