How to Set Up Bottom Sensing in Multisamplers

Answer

This Information Applies To: Agilent G7167A/B, G5668A, G7137A, and G4767A Multisamplers

Issue

The bottom sensing feature in Agilent OpenLab Software is used to detect depths of vials or plates. Material of plates or vials must be able to resist the force of the needle; not all vials are suited.

Items Required

Compatible consumables for bottom sensing feature (Figure 1):

• Glass vials without inserts (such as 5182-0714)
• Glass vials with fixed inserts (such as 5188-6591)
• Glass vials with inserts without polymer feet (such as 5183-2090)
  

  
  Figure 1. Compatible vials

Incompatible consumables for bottom sensing feature (Figure 2):

• Glass vials with inserts containing polymer feet (such as 5183-2088), as moving polymer feet could affect injection precision
• Polypropylene vials (such as 5182-0567), as it could lead to clogging of the needle with bottom sensing
• High-recovery vials (such as 5183-2030) nor with micro-V (such as 5184-3550), as its shape could damage the needle tip with bottom sensing
  
  

  
  Figure 2. Incompatible vial
  

Steps to Follow

The Vial/Well Bottom Sensing feature allows the needle to detect nonuniform well bottoms and adjusts the depth of the needle position above the detected bottom of the vial or well. You can use this feature combined with the Offset to customize the draw position of the needle.

Right click the sampler > select Method, under Advanced > Needle Height Position, check the box Use Vial/Well Bottom Sensing to turn on this feature (see Figure 3). 
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.

Offset

This option 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.

• The default position (Offset = 0.0) is a vertical offset of +2.0 mm.
• Use a negative offset to touch the vial/well bottom with the needle.

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.

Table 1. Needle Tip Position When Draw Position/ Offset = 0 for Multisamplers 

Tips: 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 in case a sample precipitate could clog it.

Learn how to effectively operate your Agilent samplers: Multisamplers Agilent InfinityLab LC Series user manual on Agilent.com