Separate or combined prime

I have a question regarding Alliance systems.

Does it matter if I (wet) prime each line separately or if I do it combined (4x 25% composition) if the total volume is the same?

So, is 5 min@ 5ml/min prime for 100%A only (and then 100% for each remaining channel; total volume 25 ml*4 channels = 100ml) equal to 25min@ 5ml/min for 25/25/25/25 A/B/C/D? (100ml combined)?


  • Also, what is the duration and flow rate of WetPrime that you use? Waters' recommendations seem to be 5min @ 5ml/min.
  • I find the Waters defaults to be adequate. The safest, surest route is to do the lines in sequence, that way, you can be certain that each of them is wet. If you do 25% x 4 lines, it is hard to tell which one is spitting out air...
  • Pflan

    For a dry prime, you should use 100% and do each line individually.  It shouldn't matter which you use (100% or 25/25/25/25) for a wet prime.  The Alliance has a System Prep function that can run this for the user.  It usually comes down to preference.  

    I'm not sure that 5min is required to wet prime, it really depends on how much air is in the line and the type of solvent (aqueous usually requiring more time than organics).  
  • Gonzalo
    Hi DavidHPLC, as Dan_Ramlose said, it is safest to wet-prime lines in sequence (starting with de lowest viscocity solvent to help remove air easier) to tell which line are air bubbles coming from. Waters' default flow rate is fine (5 ml/min) but you should consider that total volume of a solvent line plus its degasser chamber is about 7.5 mL so, you should set a time enough to purge at least (or more) two volumes to ensure air removal. After all lines were purged, always perform a wet-prime at zero flow for 3 to 5 minutes to stabilize the degassing chambers, as degassing efficiency is reduced at the high wet-prime flows.

  • Always prime an HPLC system with one-channel at a time, 100% (NOT 25%). This allows you to check for proper flow rate from each channel, one-at-a time.