University of Tasmania
Browse

Factors influencing the choice of buffer in background electrolytes for indirect detection of fast anions by capillary electrophoresis

Download (475.13 kB)
journal contribution
posted on 2023-05-16, 11:18 authored by Doble, PA, Miroslav MackaMiroslav Macka, Paul HaddadPaul Haddad
The suitability of relatively slow (low absolute value of mobility) coanionic buffers in background electrolytes (BGEs) for indirect photometric detection of artions by capillary electrophoresis was investigated. As a model system, 2-(cyclohexylamino)ethanesulfonic acid (CHES) was used to buffer the indirect detection electrolyte of sodium chromate. CHES (pK(a) 9.55) is a zwitterionic molecule carrying a net negative charge depending on the pH (effective charge -0.5 at pH = pK(a)), within its useful pH buffering range CHES acted as a competing probe coanion. System peaks were induced which had deleterious effects on the detection sensitivity of slow to medium mobility anions. The mobility of the system peak was determined by the effective mobility of CHES, both of which increased with increasing pH. The peaks of analytes that migrated near or on the system peak were distorted and lost all quantitative properties. Analytes that migrated after the system peak either were not detected or reversed their responses. Analytes that migrated well before the system peak were unaffected. Consequently, the suitability of slow coanionic buffers is limited either to (i) fast anions or, (ii) a pH range much below the PK(a), where the buffering capacity is not optimal.

History

Publication title

Electrophoresis

Volume

19

Issue

12

Pagination

2257-2261

ISSN

0173-0835

Department/School

School of Natural Sciences

Publisher

Wiley-VCH Verlag

Place of publication

Germany

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the chemical sciences

Usage metrics

    University Of Tasmania

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC