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By Anonymous on Monday, May 24, 2004 - 02:55 am:
We are currently trying to use a mobile phase for a method that someone gave to us. It calls for dissolving a significant amount of sodium lauryl sulfate in a phosphate solution, adding triethylamine adjusting the pH and then bringing to volume with methanol.
The problem is that we are having a heck of a time degassing the solution before use. Our client says that they do not degas, but simply let the inline degassers do the job. We are usisg Dionex HPLC's and this does not seem to do the trick for us. We end up with too much baseline instability.
Any suggestions as to how to degas the solution would be great.
Thank you in advance for all of your help.
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By Anonymous on Monday, May 24, 2004 - 06:07 am:
Degas the water or buffer before you add the SLS. You're inline degasser should be able to take it from there.
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By DeimerlyC on Tuesday, May 25, 2004 - 08:35 am:
You didn't mention what kind of degassing you are using. I assume vacuum degas with an aspirator will generate the many bubbles you describe.
I used to prepare buffers like yours, but I used a vacuum filtration device. Whenever I sent through the aqueous portion by itself (the SLS, water, and TEA all pH adjusted) I still managed to get a lot of bubbles. They would wash down when I added my organic. To add, I didn't have much bubbling when I filtered the whole mixed solution through.
So I figure unless you need them separate, filter it all at once.
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By henrik Vogelius on Wednesday, May 26, 2004 - 04:06 pm:
If your pump got more than one degas channel, you could try connecting them in serial, so you have double effect. Or use a bluecap bottle in ultrasonic with vacuum on top, release the vacuum ones in a while.
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By Henrik Vogelius on Wednesday, May 26, 2004 - 04:09 pm:
just another thing try to dismount the solvent filter, just to be sure it's not them making vaccum, because there are blocked.
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By Anonymous on Sunday, May 30, 2004 - 10:40 pm:
My experience is : If we use surfactants like SLS, we get foam. Because of this we can not control the volume of the mobile phase, this effects the RT of the compounds eluted.
Best solution is :
Premixing of the SLS buffer to Solvent
Take required volume of Methanol (generally acetonitrile is best for SLS type buffers) into measuring cylinder and then add slowly the buffer. Shake gently and then degass.
We are currently trying to use a mobile phase for a method that someone gave to us. It calls for dissolving a significant amount of sodium lauryl sulfate in a phosphate solution, adding triethylamine adjusting the pH and then bringing to volume with methanol.
The problem is that we are having a heck of a time degassing the solution before use. Our client says that they do not degas, but simply let the inline degassers do the job. We are usisg Dionex HPLC's and this does not seem to do the trick for us. We end up with too much baseline instability.
Any suggestions as to how to degas the solution would be great.
Thank you in advance for all of your help.
-------------------------------------------------------------------------------------------------------
By Anonymous on Monday, May 24, 2004 - 06:07 am:
Degas the water or buffer before you add the SLS. You're inline degasser should be able to take it from there.
-------------------------------------------------------------------------------------------------------
By DeimerlyC on Tuesday, May 25, 2004 - 08:35 am:
You didn't mention what kind of degassing you are using. I assume vacuum degas with an aspirator will generate the many bubbles you describe.
I used to prepare buffers like yours, but I used a vacuum filtration device. Whenever I sent through the aqueous portion by itself (the SLS, water, and TEA all pH adjusted) I still managed to get a lot of bubbles. They would wash down when I added my organic. To add, I didn't have much bubbling when I filtered the whole mixed solution through.
So I figure unless you need them separate, filter it all at once.
-------------------------------------------------------------------------------------------------------
By henrik Vogelius on Wednesday, May 26, 2004 - 04:06 pm:
If your pump got more than one degas channel, you could try connecting them in serial, so you have double effect. Or use a bluecap bottle in ultrasonic with vacuum on top, release the vacuum ones in a while.
-------------------------------------------------------------------------------------------------------
By Henrik Vogelius on Wednesday, May 26, 2004 - 04:09 pm:
just another thing try to dismount the solvent filter, just to be sure it's not them making vaccum, because there are blocked.
-------------------------------------------------------------------------------------------------------
By Anonymous on Sunday, May 30, 2004 - 10:40 pm:
My experience is : If we use surfactants like SLS, we get foam. Because of this we can not control the volume of the mobile phase, this effects the RT of the compounds eluted.
Best solution is :
Premixing of the SLS buffer to Solvent
Take required volume of Methanol (generally acetonitrile is best for SLS type buffers) into measuring cylinder and then add slowly the buffer. Shake gently and then degass.
