Chromate is the most commonly used carrier electrolyte for the determination of low molecular weight and inorganic anions by capillary electrophoresis. However, chromate electrolytes are usually prepared in the sodium form and consequently have poor buffering capacity. Addition of anionic buffers that introduce competing co-anions is undesirable because they can reduce the sensitivity of indirect detection and cause interfering system peaks. An approach is demonstrated to buffer a chromate electrolyte by using a suitable buffering base as a counter-ion of the chromate. This approach does not introduce any co-anions into the background electrolyte, which is prepared by titrating the acid form of chromate to the pKa of the added base. Two buffered electrolytes were investigated containing tris(hydroxymethyl)aminoethane (pKa = 8.5) or diethanolamine, (pKa = 9.2). The analytical performance characteristics of the buffered electrolytes were compared with the unbuffered chromate electrolyte. Both systems showed similar separation selectivity, efficiency and detection sensitivity, but the buffered electrolytes showed superior repeatability for migration times and peak areas, as well as a significantly greater tolerance to alkaline sample matrices.

Item Type:	Refereed Article
Research Division:	Chemical Sciences
Research Group:	Analytical Chemistry
Research Field:	Instrumental Methods (excl. Immunological and Bioassay Methods)
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Chemical Sciences
Author:	Doble, PA (Mr Philip Andrew Doble)
Author:	Macka, M (Professor Mirek Macka)
Author:	Andersson, PE (Dr Andersson)
Author:	Haddad, PR (Professor Paul Haddad)
ID Code:	12503
Year Published:	1997
Web of Science® Times Cited:	30
Deposited By:	Chemistry
Deposited On:	1997-08-01
Last Modified:	2009-10-29
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