The use of a multichannel capillary for electrophoretic separations of mixtures of clinically important substances with contactless conductivity and UV photometric detection

Abstract

A fused-silica capillary with a common outer diameter, 360 μm, but containing seven internal channels, each 28 μm in diameter (a multichannel capillary), has been tested on electrophoretic separations of mixtures of dopamine, adrenaline, and noradrenaline, using a contactless conductivity and UV photometric detection. It has been demonstrated that the sensitivity of the detection of these neurotransmitters in multichannel capillary, in comparison with those obtained for a standard singlechannel capillary with similar cross-sectional area, is comparable to that for the contactless conductivity and is about 50% higher for the UV photometry. The sensitivity is increased without loss of the separation efficiency, in contrast to UV detection with bubble cell. Further possibilities of using a multichannel capillary are demonstrated on separations of mixtures of inorganic cations (K⁺, Ba²⁺, Na⁺, Mg²⁺, and Li⁺) and mixtures of glucose and ribose. The main advantage of multi-channel capillary in comparison with a singlechannel capillary with the same cross-sectional area becomes apparent in separations in background electrolytes of high conductivity.

Keywords: CE; Contactless conductivity detection; Multichannel capillary; Neurotrans-mitters; UV photometry detection.