Determination of Selected Components of Human Urine by Electrophoresis in Short Capillary with Hydrodynamic Sampling Controlled by Pressure Pulse
Abstract
A hydrodynamic sample introduction method controlled by pressure pulse has been proposed for short-capillary electrophoresis. In the method, the separation electrolyte flushes sample from the loop of a six-way sampling valve and is carried to the injection end of the capillary.
A short pressure impulse is generated in the electrolyte stream at the time when the sample zone is at the inlet of capillary, leading to injection of the sample into the capillary. Then the electrolyte flow is stopped and the separation voltage is turned on.
The amount of sample introduced to the capillary is controlled by the duration of the pressure pulse. The method was used in the determination of ammonia, creatinine, uric acid and hippuric acid in human urine.
The determination was performed in a capillary with an overall length of 10.5 cm, in two separation electrolytes with compositions 50 mM MES + 5 mM NaOH (pH 5.1) and 1 M acetic acid + 1.5 mM crown ether 18-crown-6 (pH 2.4). A dual contactless conductivity/UV spectrometric detector was used for the detection.