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 m M), 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 m M 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.