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Buffered chromate electrolyte for separation and indirect detection of inorganic anions in capillary electrophoresis

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posted on 2023-05-16, 10:59 authored by Doble, PA, Miroslav MackaMiroslav Macka, Andersson, PE, Paul HaddadPaul Haddad
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.

History

Publication title

Analytical Communications

Volume

34

Issue

11

Pagination

351-353

ISSN

1359-7337

Department/School

School of Natural Sciences

Publisher

The Royal Society of Chemistry

Place of publication

United Kingdom

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the chemical sciences

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