QUANTITATIVE-ANALYSIS IN CAPILLARY ZONE ELECTROPHORESIS USING ION-SELECTIVE MICROELECTRODES AS ON-COLUMN DETECTORS

Inorganic and organic cations can be quantified using capillary zone e lectrophoresis with an ion-selective microelectrode as on-column detec tor. This is illustrated by determining the linear calibration plots f or potassium, sodium, rubidium, calcium, and dopamine in the range of 10(-4)-10(-3) M and for histamine in the range of 10(-5)-10(-4) M, whe re imidazole and potassium were used as internal standards. Quantifica tion of the potassium concentration in blood plasma is shown by use of both internal standard and external calibration plot. By delogarithmi zing the emf values of the ISME response and integrating the resulting curve, a linear relationship between integral and analyte quantity is obtained. The linear function between this integral and the specific resistance of the electrokinetically injected sample solution is expla ined by theory based on transport numbers. By computer simulation, exp erimental response times of the ISME detector are shown to be short en ough to ensure undistorted peak shapes and reproducible integrals.