Very Fast Electrophoretic Separation of Neurotransmitters on Commercial Instruments Using a Coupled Capillary
Abstract
A capillary formed by connecting of two capillaries with different inner diameters (25 and 100 µm) was tested for electrophoretic separation at high electric field intensities. The laboratory made coupled capillary was directly placed into the cassette of Agilent CE apparatus and was tested for separation of dopamine, noradrenaline and adrenaline in a background electrolyte of 20 mM citric acid/NaOH, pH 3.2.
An intensity of 2.7 kV cm-1 was attained in the separation part of the capillary, which is 2.9 times more than maximum intensity value attainable in the common capillary with the shortest possible length at maximum voltage +30 kV. At these high electric field intensities, the migration times were 12.3 s (dopamine), 12.8 s (noradrenaline), 13.3 s (adrenaline); and the attained separation efficiencies were between 2350 and 2760 plates s-1.