Direct amperometric determination of lactate at a carbon fiber bundle microdisk electrode by capillary zone electrophoresis

摘要

Capillary zone electrophoresis was employed for the determination of lactate using end-column amperometric detection at a carbon fiber bundle microdisk electrode. The optimum conditions of separation and detection are 3.6 * 10~(-3) mol/l Na_2HPO_4-1.4 * 10~(-3) mol/l NaH_2PO (pH 7.2) for the buffer solution, 18 kV for the separation voltage and 1.60 V versus the saturated calomel electrode for the detection potential. The limit of detection is 7.6 * 10~(-7) mol/l or 1.7 fmol (S/N = 3) and the linear range is 1.7 * 10~(-6) - 8.2 * 10~(-4) mol/l for the injection voltage of 6 kV and injection time of 5 s. The RSD is 1.8% for the migration time and 3.3% for the electrophoretic peak current. The method was applied to the determination of lactate in human saliva. The recovery of the method is between 95 and 109%.