Is this BSM plot normal?

<p> Hi, All</p><p></p><p>I am working on UPLC-MS analysis and noticed the MS signal intensity dropped abruptly and significantly (100 times lower) during the gradient HPLC analysis. I did all the trouble shooting and is confident that MS is working well.</p><p></p><p>This leads me to believe that the UPLC is not pumping as it should be during the gradient. (I also tried isocratic at 2%B, the MS intensity remains constant). I had difficulty to attach the BSM plot here, but I enclosed the figure in the ppt. Can anyone help me to take a look? This is 2% B at 50uL/min.</p><p></p><p>Dongdong</p>


  • I work with Hclass so am not very familar with the quatenary pump system but your system pressure should not be jumping up every time your primary pump delivers.  At least it does not for me.  I suggest running a pump leak test (again not sure if this works the same on your system) but you go to Maintain->Leak Test... under "Quatenary pump manager" in the Aquity console.  The mini pressure drops during priming in your accumulator pumps also strikes me as unusual.

  • rune


    Looking at your pressure trace during priming the pressure drops on the accumulator pump could be a problem with the check valve on the accumulator. On the other hand the pressure trace from the delivery of 50ul at 98/2 A/B looks quite normal and good. I notice that the pressure ripple during the past minutes is down to 8 psi and this is actually showing excellent pressure stability. The slight pressure increase (8 psi) on the accumulator and system pressure when the primary is delivering is quite normal. Are the retention times stable ?  If yes I don't think the MS intensity issue is related to a problem with the pump.

    best regards