Nonaqueous electrophoresis microchip separations: Conductivity detection in UV-absorbing solvents

Joseph Wang, Martin Pumera

Research output: Contribution to journalArticlepeer-review

55 Citations (Scopus)


The use of organic solvents in microfabricated capillary electrophoresis (CE) devices is demonstrated in connection with the separation of aliphatic amines in pure dimethylformamide, dimethylacetamide, dimethyl sulfoxide, or propylene carbonate media. Contactless conductivity detection is employed for monitoring the separated solutes in these UV-absorbing solvents. The effect of the physicochemical properties of the organic solvent upon the migration behavior is investigated. The apparent mobility increases nearly linearly with the reciprocal of the solvent viscosity, while the electroosmotic mobility increases in a linear fashion with the dielectric constant/viscosity ratio. Some deviation from theoretical predictions is observed using propylene carbonate. The nonaqueous CE microchip offers high separation efficiency, reflected in plate numbers ranging from 93 680 to 127 680, using a separation voltage of +3000 V, a dimethylformamide medium, and a contactless conductivity detection. Experimental parameters affecting the analytical performance of the nonaqueous CE/conductivity microchip are examined. Calibration and precision experiments indicate a linear and reproducible response. Such use of organic solvents can benefit microchip separations through extended scope (toward nonpolar solutes) and tunable selectivity.

Original languageEnglish
Pages (from-to)341-345
Number of pages5
JournalAnalytical Chemistry
Issue number2
Publication statusPublished - 2003 Jan 15

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry


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