ghost peaks in first blank, but not second

[aneskvi]

Hi!
We are having a problem with distubing peaks in our chromatograms. We know its detergent and PEG, but what i think is weird, is that when im running tests i get a big disturbing peak at the first two or so runs, but the rest are fine.. even when im running the same injection, the same mobil face, and the same time and gradient.

Im also cleaning the system befor the run, and using the same the day after, but still get it in the first two or three chromatograms.. and running it on the mobilphase for about 30-40 minutes befor starting the run..

Mobilphase A: 16/84 ACN/Phosphate buffer
Mobilephase B: 70/30 ACN/PB

Only running Mobilphase as a test:

1: Mobilphase - inject control (big top)
2: Mobilphase - inject control (big top)
3: Mobilphase - inject control (top)
4: Mobilphase - inject control (small top)
5: Mobilphase - inject control
6: Mobilphase - inject control

And then im doing the same thing the day after on the same system, not cleaning it, only puring with mobilphase, and starting it with mobilphase befor the run.. and i still get the same results..

Im trying to upload pictures, but it wont work..

(Agilent 1100)

[dblux_]

...Im trying to upload pictures, but it wont work..

viewtopic.php?f=1&t=2617

[aneskvi]

...Im trying to upload pictures, but it wont work..

viewtopic.php?f=1&t=2617

does not work..

[dblux_]

does not work..

If you read hint you should recognize this picture

[aneskvi]

I only see X where the photo should be.. I can se the UV, but not any other picture..

[dblux_]

I only see X where the photo should be.. I can se the UV, but not any other picture..

Strange. Anyway, if you want to post pictures just type their url addresses in a post in a form http://tinypic.com/dwt1rk.png
If you don't see this picture after clicking the link then you may try to clean cache files of your browser.

[Consumer Products Guy]

I can't cooment on the uploading stuff, but I DO see the UV detector diagram posted above.

Hi!
We are having a problem with disturbing peaks in our chromatograms. We know its detergent and PEG

I'm not so sure that you should worry about this; it was not uncommon for us to have to make a few injections before things would become consistent. Which PEG are you dealing with, and are you trying to elute as a single peak or separate into its component peaks?

Like are you trying to assay how much PEG is in your detergent product?

[BostonFSE]

Ive had success using a "magic mix" HPLC flushing solution:
50%IPA, 25%ACN, 10%DCM 15% cyclohexane

https://www.agilent.com/cs/library/cert ... H-0084.pdf


be sure to remove column and have the pump out waste go to a beaker. try flushing overnight at slow flow 0.2 ml/min or so

How do you know its PEG without a MS? If its PEG on an MS, I would spray the source overnight with MEOH only. You could run pump out directly to source to isolate if pump is contaminated, then add the ALS etc to determine which module has PEG

[BostonFSE]

Ive had success using a "magic mix" HPLC flushing solution:
50%IPA, 25%ACN, 10%DCM 15% cyclohexane

https://www.agilent.com/cs/library/cert ... H-0084.pdf


be sure to remove column and have the pump out waste go to a beaker. try flushing overnight at slow flow 0.2 ml/min or so

How do you know its PEG without a MS? If its PEG on an MS, I would spray the source overnight with MEOH only. You could run pump out directly to source to isolate if pump is contaminated, then add the ALS etc to determine which module has PEG