-
- admin
- Site Admin
-
- Posts: 647
- Joined: Wed Aug 11, 2004 12:19 am
By Grrr_aham on Monday, August 9, 2004 - 03:39 am:
We routinely use Sodium tetraborate/HCl pH 8.5 as a buffer in which we derivatise our amino acids. We are cursed with a high ammonia reading in our blanks which I have traced to this buffer mix. Our water is fresh Milli U /synergy 185 and is not the problem.
I would be a happy man if someone could help us on this problem.
Thanks!
-------------------------------------------------------------------------------------------------------
By DeimerlyC on Wednesday, August 11, 2004 - 01:25 pm:
A few questions:
Is this a vendor method?
Does your method use chromatography or just a UV-Vis?
Did you see if there are any ammonia readings when you use just Sod Borate or just HCl in water?
What I don't get is you have ammonia in a sitution where none of the compounds have nitrogen. If it is truly ammonia, then I would have to say it comes from the air if not the reagents themselves.
You're not creating matter, are you ?
-------------------------------------------------------------------------------------------------------
By grrr_aham on Thursday, August 12, 2004 - 06:58 am:
Yes it is a vendor method (copied from the original papers by Cohen and van Wandelen) which we are trying to run cheaply by making our own buffers etc.
The ammonia is from Ammonium salts either in the HCl or Na Borate I think. I am going to try making the Na Borate from NaOH and Boric acid to see if this helps. The HCl is used to adjust the pH.
Removal of ammonium by Cation exchange should work if I start with these chemicals.
The Vendors Borate buffer is clean, so there must be a way!
It is out there somewhere
-------------------------------------------------------------------------------------------------------
By DeimerlyC on Friday, August 13, 2004 - 09:32 am:
Can you post your eluent prep? If there is indeed NH3 in your salt maybe you can find a different way to get the same end.
Further questions: Why can't you get your sodium tetraborate as a salt by itself? Do you need ammonium hydroxide in your prep, whereas then you pH adjust with HCl?
I hope you don't have to clean up your MP prior to use!
Oooohhh, just a thought! Maybe you can install a cartridge that soaks up ammonia between your pump and your autosampler, like a SPE filter. I think they make them.
-------------------------------------------------------------------------------------------------------
By Jimmy on Sunday, August 15, 2004 - 07:50 pm:
Aham,
Could you polease tell me how to clean ammonium in presence of sodium by ion exchange?
-------------------------------------------------------------------------------------------------------
By HW Mueller on Wednesday, August 18, 2004 - 02:08 am:
How did you make sure that the ammonia(um) is in your mobile phase? For instance, FMOC derivatization of amino acids always produces some derivatized ammonia.
We routinely use Sodium tetraborate/HCl pH 8.5 as a buffer in which we derivatise our amino acids. We are cursed with a high ammonia reading in our blanks which I have traced to this buffer mix. Our water is fresh Milli U /synergy 185 and is not the problem.
I would be a happy man if someone could help us on this problem.
Thanks!
-------------------------------------------------------------------------------------------------------
By DeimerlyC on Wednesday, August 11, 2004 - 01:25 pm:
A few questions:
Is this a vendor method?
Does your method use chromatography or just a UV-Vis?
Did you see if there are any ammonia readings when you use just Sod Borate or just HCl in water?
What I don't get is you have ammonia in a sitution where none of the compounds have nitrogen. If it is truly ammonia, then I would have to say it comes from the air if not the reagents themselves.
You're not creating matter, are you ?
-------------------------------------------------------------------------------------------------------
By grrr_aham on Thursday, August 12, 2004 - 06:58 am:
Yes it is a vendor method (copied from the original papers by Cohen and van Wandelen) which we are trying to run cheaply by making our own buffers etc.
The ammonia is from Ammonium salts either in the HCl or Na Borate I think. I am going to try making the Na Borate from NaOH and Boric acid to see if this helps. The HCl is used to adjust the pH.
Removal of ammonium by Cation exchange should work if I start with these chemicals.
The Vendors Borate buffer is clean, so there must be a way!
It is out there somewhere
-------------------------------------------------------------------------------------------------------
By DeimerlyC on Friday, August 13, 2004 - 09:32 am:
Can you post your eluent prep? If there is indeed NH3 in your salt maybe you can find a different way to get the same end.
Further questions: Why can't you get your sodium tetraborate as a salt by itself? Do you need ammonium hydroxide in your prep, whereas then you pH adjust with HCl?
I hope you don't have to clean up your MP prior to use!
Oooohhh, just a thought! Maybe you can install a cartridge that soaks up ammonia between your pump and your autosampler, like a SPE filter. I think they make them.
-------------------------------------------------------------------------------------------------------
By Jimmy on Sunday, August 15, 2004 - 07:50 pm:
Aham,
Could you polease tell me how to clean ammonium in presence of sodium by ion exchange?
-------------------------------------------------------------------------------------------------------
By HW Mueller on Wednesday, August 18, 2004 - 02:08 am:
How did you make sure that the ammonia(um) is in your mobile phase? For instance, FMOC derivatization of amino acids always produces some derivatized ammonia.
