What are the MS tune page settings during instrument setup of a Xevo G3 QTof controlled by waters_connect? - WKB276398

ENVIRONMENT

• Xevo G3 QTof
• waters_connect 3.1 and later
• Xevo G3 QTof waters_connect driver 1.1 and later

ANSWER

Instrument setup of a Xevo G3 QTof mass spectrometer under waters_connect software platform includes the following automated steps:

1.  ADC setup

No MS fluidics are used. 

2. Detector setup (detector voltage check followed by detector gain and ion area optimization)

Direct infusion of leucine enkephalin solution at 200 pg/µL concentration shall be used only via the reference sprayer (reservoir B). Three critical parameters from the current MS tune page will be overridden by the waters_connect software: sampling cone voltage, reference capillary voltage, and reference flow rate. The software will set them to 120 V, 3 kV (2.5 kV in negative ion), and 10 (or 20) µL/min, respectively.

Using a lower concentration of leucine enkephalin solution at that stage will cause the instrument setup/detector setup step to fail because the required signal height on m/z 556.28/554.26 will drop into the MS background when the sample cone voltage ramps up. 

2. Beam check

As above, leucine enkephalin solution at 200 pg/µL is required.

3. Mass calibration (depending on which mass calibration profile has been selected by the end-user)

Ensure that collision cell RF/gain are set to 150 V and 10 V, respectively, in order to enhance low mass ion transmission.

Direct infusion of the relevant calibrant solution will be used only via the sample sprayer (reservoir C). Three critical parameters from the current MS tune page will be overridden by the waters_connect software: sampling cone voltage, sample capillary voltage, and sample flow rate. The software will set them to 40 V, 3 kV (2.5 kV in negative ion), and 10 (or 20) µL/min, respectively.

Small molecule application, m/z 1200 and m/z 2000, requires sodium formate solution 0.5 mM.

Large molecule application, m/z 5000 and m/z 8000, requires sodium iodide solution 2 µg/µL.

16-kDa application, m/z 16000, requires cesium iodide solution 50 ng/µL.

 

ADDITIONAL INFORMATION

There should be no limitation for using a lower concentration than 200 pg/µL of leucine enkephalin solution (20 - 50 pg/µL) during LC-MS runs as long as the Xevo G3 QTof mass spectrometer gives adequate and stable signal height intensity on m/z 556.28/554.26 ions for positive-ion and negative-ion polarities, respectively.

However, the above depends on the following parameters:

• LC outlet (0.05 - 0.8 mL/min)* and reference fluidics flow rate (10 - 20 µL/min)** 
  • * User's Method Development   ** Tuneable     
• Hot gas and solvent flow turbulence induced by the overall source settings (analyte and reference) into the source enclosure
  • For more information, see the Xevo G3 QTof Overview and Maintenance Guide document - Flow rates for the Xevo G3 QTof system
• The capillary tip protrusion from the reference sprayer nozzle

Reminder: In contrast to IntelliStart functionality under MassLynx software control, there is no automated reference (or LockSpray or Lock Mass) beam setup under waters_connect. Therefore, the reference beam must be checked manually before running an LC-MS analysis.

Refer to the Xevo G3 QTof Overview and Maintenance Guide for more information.