-
- admin
- Site Admin
-
- Posts: 647
- Joined: Wed Aug 11, 2004 12:19 am
By Anonymous on Monday, November 24, 2003 - 05:23 am:
Hi,
I am in need of some advise. I am currently running a gradient method using mobile phase A : 250 Mm Amm. Formate and mobile phase B: 100%ACN. My column is a Glycosep N (250x4.6mm).I am running the method on a Waters 2695 and 2475 Flouresence detector (With Empower Software), my expected sample chromatogram contains 9 peaks of intrest. Sample chromatograms achieved are perfect but my method states that a water injection after a sample should be free of contamination.The blank water (HPLC Grade) contains the definate profile of my sample at a % carryover of ~0.15. I have tried flushing the system and have tried different gains and attenuation settings on the detector. Does anyone have any advise on where to go next?
Thanks.
-------------------------------------------------------------------------------------------------------
By Anonymous on Monday, November 24, 2003 - 08:31 am:
You need to adjust your needlewash solution. Try the following needle wash ACN/water/IPA 5:1:1. As well, use the extended needle wash option in the Empower method. Your needle wash frit may be contaminated beyond help at this point, change it out and make the other changes.
-------------------------------------------------------------------------------------------------------
By Anonymous on Tuesday, November 25, 2003 - 02:14 am:
Hi,
Thanks for your reply, I should have said that this system is only a few mths old, do you think the frit could be gone so quickly??? Also this is a tech transfer... 20% meoh was used as needle wash in originating site..... and they saw no carryover. They used a sat/in box hooked up to millennium 32, I'm wondering if our system hooked up to Empower is way more sensitive?? What do you think?? We have the extended needle wash set but this had no impact....
Any thoughts welcome.......
-------------------------------------------------------------------------------------------------------
By Einar Pontén - SeQuant AB on Tuesday, November 25, 2003 - 03:39 pm:
Defect injector rotor seal is another common source to this problem, although your system was new it might have been damaged. What is your injection volume and how many samples volumes are used to fill the loop (10 are recommended)?
-------------------------------------------------------------------------------------------------------
By Beppe on Wednesday, November 26, 2003 - 12:32 am:
Einar, have a look at Waters litterature. You will see that Alliance does not use a rotary valve nor requires loading more than the volume you really inject ...
-------------------------------------------------------------------------------------------------------
By Anonymous on Wednesday, November 26, 2003 - 01:00 am:
Hi everbody,
Thanks for your input, I plan to meet a waters engineer over the next few days to see what parts of the alliance could be prone to contamination and what parts can be changed.....
Any more thoughts welcome...
-------------------------------------------------------------------------------------------------------
By HW Mueller on Wednesday, November 26, 2003 - 03:36 am:
Einar, is there some study claiming that only "defective" rotary injectors produce carryover? I am absolutely sure that the many cases of carryover in this lab were obtained with fully intact injectors. It makes sense that sample is transported mechanically back and forth between solvent swept and unswept areas. It appears to be a matter of required sensitivity whether you see carryover or not.
So, Beppe, the Waters´Alliance does not have a valve with mechanically moving parts "communicating" with liquid? (Takes a while to get at the information)
This has probably been mentioned before: If you take a rotary valve with carryover apart, wash the stator and rotor, the carryover is gone. We call such valves, as well as syringes, dirt slingers.
Hans
-------------------------------------------------------------------------------------------------------
By Anonymous on Wednesday, November 26, 2003 - 06:12 am:
Beppe is quite correct, Alliance does not use the rotor/stator type of injector. This is not to say that it does not have "mechanically moving parts "communicating" with liquid", it is different than the often used fill the loop Rheodyne injector.
-------------------------------------------------------------------------------------------------------
By A.Mouse on Wednesday, November 26, 2003 - 12:39 pm:
HW: Carryover is sometimes caused by adsorption of the sample to the seal material. Thus it can be very specific to the injector mechanism. Usually, steel is not the problem.
Of course Beppe is correct, it does not apply to the Alliance
-------------------------------------------------------------------------------------------------------
By HW Mueller on Thursday, November 27, 2003 - 06:01 am:
It seems that the problem is not so much the material but the film of liquid that is dragged in between mechanically movable parts, like a stator and rotor, a piston, etc. Of course, an unhappy choice of material should make this worse.
Also, as I hinted, it is strongly dependent on sensitivity of the detection, is there anybody out there working with radioactivity and autosamplers? No carryover??
-------------------------------------------------------------------------------------------------------
By Andreas Neumaier on Friday, November 28, 2003 - 03:28 am:
When a carryover problem is observed with an Waters Alliance (or 717 +) autosampler, it could be related to a defect Valve 3. You should call Waters Service and ask them.
-------------------------------------------------------------------------------------------------------
By Anonymous on Friday, November 28, 2003 - 03:41 am:
Thanks,
Will get on to Waters abt that.
-------------------------------------------------------------------------------------------------------
By Basil on Friday, November 28, 2003 - 04:48 am:
Talking about carry over on Agilent 1100. I'm having big problems with a 6 months old equipment.
With an old one I don't have the same problem with carry over.
They said that they don't have changed anything in the system injection from the old ones.....
After cleaning all the system carry over seams to be lower but after two days working it comes again.
Any idea would be appreciated..
Thanks
-------------------------------------------------------------------------------------------------------
By marcel on Thursday, July 15, 2004 - 11:37 pm:
Dear Basil,
We're dealing with almost the same issue you described in your message of November 28, 2003. We also using an Agilent 1100 autosampler. I was wondering if you already solved your problem in the meantime.
Thanks for your help in advance,
Marcel
Hi,
I am in need of some advise. I am currently running a gradient method using mobile phase A : 250 Mm Amm. Formate and mobile phase B: 100%ACN. My column is a Glycosep N (250x4.6mm).I am running the method on a Waters 2695 and 2475 Flouresence detector (With Empower Software), my expected sample chromatogram contains 9 peaks of intrest. Sample chromatograms achieved are perfect but my method states that a water injection after a sample should be free of contamination.The blank water (HPLC Grade) contains the definate profile of my sample at a % carryover of ~0.15. I have tried flushing the system and have tried different gains and attenuation settings on the detector. Does anyone have any advise on where to go next?
Thanks.
-------------------------------------------------------------------------------------------------------
By Anonymous on Monday, November 24, 2003 - 08:31 am:
You need to adjust your needlewash solution. Try the following needle wash ACN/water/IPA 5:1:1. As well, use the extended needle wash option in the Empower method. Your needle wash frit may be contaminated beyond help at this point, change it out and make the other changes.
-------------------------------------------------------------------------------------------------------
By Anonymous on Tuesday, November 25, 2003 - 02:14 am:
Hi,
Thanks for your reply, I should have said that this system is only a few mths old, do you think the frit could be gone so quickly??? Also this is a tech transfer... 20% meoh was used as needle wash in originating site..... and they saw no carryover. They used a sat/in box hooked up to millennium 32, I'm wondering if our system hooked up to Empower is way more sensitive?? What do you think?? We have the extended needle wash set but this had no impact....
Any thoughts welcome.......
-------------------------------------------------------------------------------------------------------
By Einar Pontén - SeQuant AB on Tuesday, November 25, 2003 - 03:39 pm:
Defect injector rotor seal is another common source to this problem, although your system was new it might have been damaged. What is your injection volume and how many samples volumes are used to fill the loop (10 are recommended)?
-------------------------------------------------------------------------------------------------------
By Beppe on Wednesday, November 26, 2003 - 12:32 am:
Einar, have a look at Waters litterature. You will see that Alliance does not use a rotary valve nor requires loading more than the volume you really inject ...
-------------------------------------------------------------------------------------------------------
By Anonymous on Wednesday, November 26, 2003 - 01:00 am:
Hi everbody,
Thanks for your input, I plan to meet a waters engineer over the next few days to see what parts of the alliance could be prone to contamination and what parts can be changed.....
Any more thoughts welcome...
-------------------------------------------------------------------------------------------------------
By HW Mueller on Wednesday, November 26, 2003 - 03:36 am:
Einar, is there some study claiming that only "defective" rotary injectors produce carryover? I am absolutely sure that the many cases of carryover in this lab were obtained with fully intact injectors. It makes sense that sample is transported mechanically back and forth between solvent swept and unswept areas. It appears to be a matter of required sensitivity whether you see carryover or not.
So, Beppe, the Waters´Alliance does not have a valve with mechanically moving parts "communicating" with liquid? (Takes a while to get at the information)
This has probably been mentioned before: If you take a rotary valve with carryover apart, wash the stator and rotor, the carryover is gone. We call such valves, as well as syringes, dirt slingers.
Hans
-------------------------------------------------------------------------------------------------------
By Anonymous on Wednesday, November 26, 2003 - 06:12 am:
Beppe is quite correct, Alliance does not use the rotor/stator type of injector. This is not to say that it does not have "mechanically moving parts "communicating" with liquid", it is different than the often used fill the loop Rheodyne injector.
-------------------------------------------------------------------------------------------------------
By A.Mouse on Wednesday, November 26, 2003 - 12:39 pm:
HW: Carryover is sometimes caused by adsorption of the sample to the seal material. Thus it can be very specific to the injector mechanism. Usually, steel is not the problem.
Of course Beppe is correct, it does not apply to the Alliance
-------------------------------------------------------------------------------------------------------
By HW Mueller on Thursday, November 27, 2003 - 06:01 am:
It seems that the problem is not so much the material but the film of liquid that is dragged in between mechanically movable parts, like a stator and rotor, a piston, etc. Of course, an unhappy choice of material should make this worse.
Also, as I hinted, it is strongly dependent on sensitivity of the detection, is there anybody out there working with radioactivity and autosamplers? No carryover??
-------------------------------------------------------------------------------------------------------
By Andreas Neumaier on Friday, November 28, 2003 - 03:28 am:
When a carryover problem is observed with an Waters Alliance (or 717 +) autosampler, it could be related to a defect Valve 3. You should call Waters Service and ask them.
-------------------------------------------------------------------------------------------------------
By Anonymous on Friday, November 28, 2003 - 03:41 am:
Thanks,
Will get on to Waters abt that.
-------------------------------------------------------------------------------------------------------
By Basil on Friday, November 28, 2003 - 04:48 am:
Talking about carry over on Agilent 1100. I'm having big problems with a 6 months old equipment.
With an old one I don't have the same problem with carry over.
They said that they don't have changed anything in the system injection from the old ones.....
After cleaning all the system carry over seams to be lower but after two days working it comes again.
Any idea would be appreciated..
Thanks
-------------------------------------------------------------------------------------------------------
By marcel on Thursday, July 15, 2004 - 11:37 pm:
Dear Basil,
We're dealing with almost the same issue you described in your message of November 28, 2003. We also using an Agilent 1100 autosampler. I was wondering if you already solved your problem in the meantime.
Thanks for your help in advance,
Marcel
