Pressure in HPLC Range

I have a problem when diltiazem hydrochloride is analyzed according to USP, it asks me for a 2.1 mm × 15 cm column; 1.7 µm packing L1 if I look at the usp information it uses an ACQUITY UPLC BEH C18 2.1 mm x 15 cm, 1.7 µm column. Manufacturer, obviously the column is for a UPLC but the USP asks me to use an HPLC but in the HPLC Alliance that I have it does not allow me to have a pressure greater than 5000 so I cannot perform the analysis. Is there any way to increase the maximum pressure to 15000


  • lizh
    The column defines the LC method, and thus even if you could set the pressure on the Alliance, the volume of the system, and the detector flow cell would be too high for you to achieve good chromatographic results. 2.1 mm ID columns require lower dispersion as well as higher pressure. The high pressure is just a side-effect of the small particles. You must scale the separation to a 3.5 mm or larger column that is appropriate for HPLC. However, if the monograph calls for this column, this is specifying that UPLC system is required. There are calculators that can help you do that. I would check that the L1 is only 2.1 mm ID and/or if another method is available.