Simultaneous determination of δ-aminolevulinic acid, porphobilinogen, levulinic acid and glycine in culture broth by capillary electrophoresis

Capillary electrophoretic simultaneous determination of a mixture containing δ-aminolevulinic acid, porphobilinogen, levulinic acid and glycine was investigated. With increases in the sodium tetraborate buffer concentration (5–70 mM), resolution of the four components was improved, but the migration time was increased. Alternatively, with increases in the applied voltage (5–22.5 kV), a shortened migration time was seen but this adversely affected resolution. The components were separated with high resolution by using a fused-silica capillary column (75 cm×75 μm I.D.) filled with 30 mM sodium tetraborate buffer (pH 9.3–9.4) under the applied voltage of 20 kV (constant voltage mode). When the established method was applied to the culture broth of Rhodopseudomonas sphaeroides, a photosynthetic bacterium, the four components mentioned above were separated with good resolution. Furthermore, the use of this method would provide a fast, sensitive and specific method for monitoring the administration of δ-aminolevulinic acid in photodynamic cancer therapy, for the measurement of δ-aminolevulinic acid dehydratase activity in erythrocytes, and for testing the δ-aminolevulinic acid assay and for impurities in drug formulation.