Modifying an Acquity QDa sugars application

My lab has inherited a H-class UPLC and QDa detector.  We want to use the system for the analysis of sugars.  I found one Waters application for an Acquity UPLC with QDa detector.

Unfortunately, I am unable to see any sugar peaks.  I've been looking at fructose, glucose, maltose, and sucrose.

The method uses an Acquity BEH Amide column, 1.7 um, 2.1 x 100 mm.  I am using an Acquity BEH Amide column, 1.7 um, 2.1 x 30 mm.  The first time I tried this method, I didn't change anything to account for the shorter column.  I assumed the sugar peaks will have earlier retention times, but should still be there.  I saw no peaks.  My standards looked similar to the ACN blank.

I then tried the method a second time with some adjustments.  We lowered the flow rate from 0.25 ml/min to 0.10 ml/min, and increased the run time from 12 minutes to 20 minutes.  The idea was a slower flow rate to account for the shorter column, and a longer run time to go with the slower flow rate.  Still no sugar peaks.  

I am new to the Acquity QDa detector and Empower software.  My prior mass spec experience has been with Agilent 6400 series triple quads and Masshunter software.  This may be a large part of my difficulties.  

The application note is: Profiling Mono and Disaccharides in Juice, Wine, Beer, and Cider using the ACQUITY UPLC H-class system and the ACQUITY QDa detector.




Comments

  • Hi Mike, depeneding on the background, you peaks might be to small to be directly visible, have you tried EICs/ directly monitionring your masses in SIRs? I had a similiar issue when i first started to detect my small molecules, as they are not visible against the baseline noise but become clearly visible in the SIR
  • Hello Kuro, thank you for your reply.  I have been monitoring for the masses in SIRs. It may be that the flow rate I am using is too high for this short column.  I am making another try, with the flow rate cut in half.

    Kuro, if you don't mind me asking, what small molecules have you been looking for?  
  • Hi MikeL42,

    Is there a reason you can't use the longer column?  I am asking around within Waters with various experts.  But in general Carbohydrate methods are very challenging.  That particular method took a long time to develop.  While I am waiting to see if there are some additional insights here at Waters - could you try the column and parameters in the original method?


  • Hi Pflan,
    I have the longer column now, it came in a week ago.  Since then I have been trying the column and parameters in the original method.  I am seeing small ragged peaks that could be fructose, glucose, maltose, and sucrose.  
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