Figure 29. Two-Piece Fingertight Fitting And Loosened Sample Inlet Adapter Fitting - Thermo Scientific LTQ Series Hardware Manual

5
Maintenance
Ion Source Probe Maintenance
Trimming the ESI Sample Tube
58 LTQ Series Hardware Manual
Operating the mass spectrometer with acetonitrile in the mobile phase can cause elongation of
the polyimide coating on the fused-silica sample tube. If the polyimide coating has elongated
past the end of the electrospray needle, cut and reposition the end of the sample tube.

To cut and reposition the end of the sample tube
1. Place the mass spectrometer in Standby mode (see
temperature. See the temperature cautionary statement on
2. Remove the ESI probe from the API source housing.
For instructions, refer to Chapter 2, "Setting Up the API Source," in the LTQ Series
Getting Started Guide.
3. Loosen the red fitting of the two-piece fingertight fitting that secures the position of the
sample tube and the safety sleeve at the ESI probe sample inlet
Note When the nut and ferrule assembly are properly positioned in the receiving
port, the receiving port compresses the ferrule so that it fits snugly to the tubing.
When you loosen the fitting, the receiving port does not compress the ferrule and the
tubing is free to move.

Figure 29. Two-piece fingertight fitting and loosened sample inlet adapter fitting

4. Gently pull back on the sample tube to free it from the ferrule.
5. Push the sample tube forward so that it extends beyond the end of the electrospray
needle.
6. Using the fused-silica cutting tool, cut a small length (4–5 mm) of sample tubing and
then under magnification check that the end is squarely cut.
Receiving port of the sample inlet adapter fitting
Ferrule for 190 μm OD tubing
One-wing, red, Fused-silica
fingertight fitting sample tube
page 35) and let it cool to room
page 57.
(Figure 29).
Thermo Scientific