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.
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.
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Comments
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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 SIR0
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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?0 -
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?0 -
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.0
