Rapid Determination of Methotrexate and 7-Hydroxymethotrexate in Serum and Cerebrospinal Fluid by Radial Compression Liquid Chromatography

Abstract

A rapid, specific and sensitive radial compression reverse phase liquid chromatographic method for the analysis of [the antineoplastic drug] methotrexate and 7-hydroxymethotrexate in serum and CSF is reported. A mobile phase consisting of acetonitrile-methanol-pH 3 phosphate (8:15:77) at 6 ml/min flow rate was employed. The UV detector was set at 317 nm; folic acid was used as an internal standard. A rapid extraction of methotrexate and 7-hydroxymethotrexate was performed using Sep-Pak cartridges with high extraction efficiency for both compounds. Patients serum and CSF samples were analyzed by the described method; the concentrations of methotrexate were compared to those obtained by an enzyme immunoassay. No interference from other metabolites or anticancer drugs in the described assay was observed.