Needle Height Position

Offset

This is a vertical offset that enables you to position the needle a specific distance (in mm) away from its standard position. The Offset is calculated from the bottom of the vial/well, with a slight amount of clearance to cover tolerances.

Use a positive offset to raise the needle higher in the vial/well to clear precipitates on the bottom of the vial/well, or to select one phase of a biphasic sample.

Use a negative offset to touch the vial/well bottom with the needle.

NOTE: The default position (Offset = 0.0) is a vertical offset of +2.0 mm.

Use Vial/Well Bottom Sensing

This feature allows the needle to detect non-uniform well bottoms, and adjusts the depth of the needle position above the bottom of the vial or well.

You can use Vial/Well Bottom Sensing in combination with the Offset to customize the draw position of the needle.

To turn on Vial/Well Bottom Sensing, mark the check box. The default setting is cleared.

When Vial/Well Bottom Sensing is disabled, the offset is calculated from the stored dimensions of the plate.

When Vial/Well Bottom Sensing is enabled, the offset is calculated from the bottom position determined by the bottom sensing of the instrument.

You may want to turn off Vial/Well Bottom Sensing to increase speed of injection, or to avoid the needle touching the bottom of the well if a sample precipitate could clog it.