1. Insert your capillary fitting into the nanoZero®, maintaining careful alignment so that the capillary fitting seal meets the conductive seal at the base of the nanoZero®.
2. Rotate the fitting one full turn using the black nut, then turn back a quarter turn. This is where the thread begins to engage. When correctly threaded, this should feel easy and smooth, with no grip or resistance.
3. If everything feels right, continue screwing in until the connection is finger tight.
   
   

• Aurora CSI & UNI columns: Hold the nanoZero® steady with a spanner and tighten your capillary fitting finger tight until you reach a firm stop - the point at which the fitting stops turning and significant additional force would be needed to continue.
• Aurora XT & XS columns: Hold the nanoZero® steady with your fingers, tighten finger tight to a firm stop, then use the leverage of the column cassette to go an extra quarter turn to fully tighten.
  
  

Using a torque tool in combination with a nanoZero® - even once - can compromise your capillary line, sometimes without any visible damage.

Once your column has been properly installed, when possible, avoid disconnecting the nanoViper®-nanoZero® union. For visual instructions on how to connect your column, see our Help Centre article ‘How to connect the nanoZero® to the nanoViper fitting’.

Pro tip: use direct flow for equilibration and installation

When setting up or equilibrating your column, always use direct flow control rather than LC vendor-based equilibration scripts. Automated scripts from your LC system can create pressure fluctuations that increase the risk of backflow. These scripts have not been fully validated for use with Aurora columns, so using them could potentially affect column performance or stability by disrupting the column bed. Direct flow keeps you in control of exactly what the column experiences at every stage.

Note: Evosep systems are an exception. Recommend installing the column and starting isocratic flow at 200 nL/min. Once solvent reaches the emitter, turn on the voltage from the mass spectrometer. Run the system at isocratic flow until the back-pressure stabilises, then wait 5 minutes after the pressure has stabilised to begin running the first blank sample.

Removing your column: drop the pressure first

When it comes time to remove your column, the key step that's easy to skip is reducing the pressure first. Because of how Aurora Series® columns are built for maximum sensitivity, backflow is a real risk if you disconnect under pressure. If backflow occurs, residue can end up in your capillary fitting/nanoZero® connection, which creates the exact kind of occlusion you were checking for earlier. 

The process:

1. Run 80% B for 5 minutes at operating flow rates
2. Reduce flow to 0.002 μL/min for 10 minutes, or until back pressure has stabilised below 10 bar
3. Set your MS system to standby mode
4. The column can now be removed from the source, and capillary line can be safely removed from the nanoZero®
   

1. Let the run finish (run a blank first if you'd like additional flushing)
2. Immediately stop the instrument after the run
3. Turn off the spray voltage and prevent idle flow (e.g., close HyStar)
4. Allow ~10–15 minutes for the column to slowly depressurise through the emitter

Troubleshooting spray instability due to capillary fitting: a practical sequence

Step 2: Clean the capillary fitting

If there is any visible occlusion or discolouration of the capillary fitting, place both ends of your capillary fitting into an Eppendorf tube of methanol and sonicate it. This can clear occlusion and restore function without needing a new line.

After cleaning the capillary fitting, did your spray performance improve? If not, try step 3.

Step 3: Try reversing the capillary line

If you'd rather not replace the line just yet, or you're working with limited spare parts you can try to reverse the line. Unexpected, but surprisingly effective: disconnect the capillary line from the column and reverse the direction of the capillary line (i.e. column end into injection valve, injection valve end into column). Because the column-side end of your capillary fitting is more prone to seal face deformation over time - from repeated use or overtightening - the UHPLC-side end tends to be in better condition - just inspect that side as well to make sure before installing. Reversing the line puts a less deformed face at the critical interface, and it's a quick, no-cost first step.

After reversing the capillary line, did your spray performance improve? If not, try step 4.

Step 4: Replace the capillary fitting

If spray instability persists after trying all the steps above, replacing your capillary fitting is the next logical step. It rules out fitting degradation as a potential cause of spray instability and gives you a clean baseline.

After replacing the capillary, did your spray performance improve? If not, please use the Troubleshooting Guide to submit your information and connect with one of our specialists. We’re here to help.

As a consumable, capillary lines have no fixed lifespan or set number of uses; it varies depending on conditions and usage. It is best to keep a few spare transfer capillary lines in stock to support troubleshooting. Consider this part of the maintenance kit for your LC. Routine cleaning of your capillary line and column between sample projects (with a solution of 1:1:1:1, Acetonitrile:Methanol:Isopropanol:Water +0.1% Formic Acid) can keep sample-related build-up from forming in the capillary and on the column. If you already refresh your LC solvents every two weeks, folding cleaning injections into that same schedule is the most practical way to make it a consistent habit without disconnecting the capillary lines. If you're not experiencing any ongoing carryover concerns, cleaning at that cadence is generally sufficient.