Rapid analysis of doxorubicin in plasma by radial compression liquid chromatography

A reversed-phase liquid chromatographic method for the analysis of doxorubicin (Adriamycin) in plasma is described. The analysis was performed on a radial compression separation system with a 10-micron phenyl cartridge. The mobile phase consisted of methanol:acetonitrile:0.001 M tetrabutylammonium phosphate (36.4:8.6:55) adjusted to pH 3.5 with 85% phosphoric acid. The flow rate was 2.8 mL/min. Fluorometric detection at excitation and emission wavelengths of 478 and 594 nm, respectively, was used. C18 sample cleanup cartridges were utilized for extraction. A doxorubicin-related compound, 4-demethoxydaunorubicin (IMI 30), was used as an internal standard. The retention times for doxorubicin and IMI 30 were 3.34 and 7.21 min, respectively. The assay was highly linear (r greater than 0.997) in the concentration range utilized in this study (i.e., 10-5,000 ng/mL). No interferences from doxorubicin metabolites or other anticancer drugs were observed. The assay is currently used for monitoring doxorubicin levels in high-risk patients.