High pressure, but new column.

I'm using the CORTECS UPLC Shield RP18, 90 Å, 1.6 μm, 2.1 × 100 mm (p/n: 186008694) with the exact same application method published by Waters for CBD, but im getting pressure over 15,000 when running at 0.7 ml/min (as published)  even before injecting samples.   My system runs at 980 psi when running with a union instead of a column at 0.5 ml/min.  I think that's somewhat normal without the column.  It is frustrating to have to run at a lower flow rate than normal despite having a new column.   Any thoughts? 


  • jmkrest
    edited March 2020
    A few things to check:

    -Is there a frit or a guard column that needs to be replaced?
    -Are you using the correct mobile phase (acetonitrile tends to have much lower pressures than methanol or methanol-water mix)?
    -Is the column heater turned on?