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what is cut off for tetraalkylammonium sal (HPLC) ?

Posted: Wed Sep 10, 2008 12:32 pm
by JOCAPEN
I m sorry friends, but I have one doubt.....I need to analysis for organic acids, but the literature recomends TBA....I know the advantages when you use this ion par, but I have been problems because the low wavelength (2100 nm UV detector) for 0,002M TBAI pH 3,5 mobile phase??
:(

Posted: Wed Sep 10, 2008 4:34 pm
by Uwe Neue
You can purchase a version of this reagent that is good for use down to 200 nm from Waters: low-UV PIC A, part number WAT084189

Tanks....

Posted: Wed Sep 10, 2008 7:49 pm
by JOCAPEN
Now, I need to check the specification about the PIC-A Waters, but are you now the criteria (TBA/ cloride/ phosfate or sulfate) for ionic compounds....

Posted: Wed Sep 10, 2008 9:09 pm
by Bruce Hamilton
Just to clarify, if I recall correctly, Waters PIC A ( tetrabutylammonium ) comes as two forms.

"Low UV PIC A" ( tetrabutylammonium hydrogen sulphate ) which can be used down to 200nm, and "PIC A" ( tetrabutylammonium phosphate ) which can be used down to 240 nm. Those cutoffs apply to the recommended concentrations.

Make sure to look at the correct product specifications. There are pure forms of tetrabutylammonium salts available from Romil, Sigma-Aldrich, and other suppliers.

Bruce Hamilton

Posted: Wed Sep 10, 2008 11:29 pm
by Uwe Neue
Ion-pair reagents have been sold by Waters since the 1970s, and the high-purity form has been sold since at least the early 1980s. Waters was a leading supplier of these reagents, whose use goes back to the work of Brian Bindlingmeyer, who was then a Waters employee, and his team.

excuses....TBA

Posted: Wed Oct 01, 2008 8:44 pm
by JOCAPEN
This question about TBA...started with the article Determination of glycolic acid in cosmetic products by solid-phase extraction and reversed-phase ion-pair high-performance liquid chromatography...this work have been used TBAI but 210 nm UV detection.....but I know this salt is no good, when used low UV....sometimes....is possible