By stephon_xu on Wednesday, May 26, 2004 - 10:02 pm:

I'm looking for separation condition of catecholamine.
Column:Perkin Elmer,Velosep RP-18,3um,100*3.2mm;
ED:BAS company.
Looking for the mobile phase condition.
I can't separate dopamine and DOPAC,HVA and 5-HIAA.
thanks!

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By Anonymous on Thursday, May 27, 2004 - 12:05 am:

http://www.gls.co.jp/application/INERTS ... LC-F03.htm

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By stephon_xu on Thursday, May 27, 2004 - 05:17 am:

thanks!
but i use electrochemical detector,not uv detector.

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By Henrik vogelius on Thursday, May 27, 2004 - 01:37 pm:

http://www.gls.co.jp/application/INERTS ... LC-F17.htm

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By Zelechonok on Thursday, May 27, 2004 - 07:48 pm:

Two similar methods with simple mobile phase H2O/ACN/TFA

http://allsep.com/makeChr.php?chr=Chr_042

http://allsep.com/makeChr.php?chr=Chr_044

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By Anonymous on Saturday, May 29, 2004 - 07:05 am:

Water/ACN/TFA mobile phases are not usually suitable for EC detection. 210 nm (as described by Zelechonok) neither offers the sensitivity or selectivity required by many (but not all) catecholamine methods.

Mr. Xu,

You need to do a little bit of research, there are many good mobile phase mixtures for cats by ECD out there in the liturature. A simple search on Google should get you started.

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By stephon xu on Saturday, May 29, 2004 - 07:50 am:

today,i have used mobile phase containing EDTA acid,methanol,camphor sulfonic acid(CSA) and chloroacetic acid.
i used 10ng/ml standard substance of catecholamine. But i can't find 5-HIAA,5-HT,HVA.
I don't know why? if the concentration of standard subatances is too low, or other reasons?
i'm newer in doing such things,and want to setup the method in two months.
could any one give me some suggestion to save my time?
Thank you very much!!!

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By Uwe Neue on Saturday, May 29, 2004 - 10:24 am:

Mr Xu,

You could save yourself a lot of time and effort by buying a standard catecholamine kit from one of the suppliers. While they are expensive, such problems as you are describing have been solved already by the pros. Such kits are commonly used in clinical analysis. Check with Waters, Chromsystems, and others!

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By Anonymous on Saturday, May 29, 2004 - 03:59 pm:

Mr Xu,

Most often, sensitivity problems are usually a matter of excess detector noise. This noise can be generated from many places and takes some time and expertise (ie experience)to reduce. In the meantime work out you chromatography using higher concentration standards.

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By stephon xu on Saturday, May 29, 2004 - 10:26 pm:

thank you Uwe Neue!
thank you all they have help me!
Today i have tried to determine the retent time of 5-HIAA,DOPAC,HVA,MHPG.
But i found their retention time all about 2.4-2.5min,such as NE.
The retention time of DA and 5-HT are 4.6min and 7.9min.
The mobile phase contain 2.2mM EDTA,and i have added 20g NaOH to resolve EDTA.Then using phosphoric acid adjust pH to 6.9.
Could any one help me to separate 5-HIAA,DOPAC,HVA,MHPG and NE?