GLC determination of floxuridine in plasma using a thermionic nitrogen detector

A specific GLC method was developed for the determination of floxuridine in plasma using the thermionic nitrogen detector. The method involves the isolation of the compound and internal standard from plasma on a strong anion-exchange column at pH 10, followed by elution with 0.3 M acetic acid in methanol. The eluate is evaporated to dryness, and the residue is dissolved in dimethyl sulfoxide and permethylated with potassium tert-butoxide and methyl iodide. The permethylated compounds are reextracted from the reaction mixture with cyclohexane-methylene dichloride (9:1). The organic solution is evaporated to dryness, the residue is dissolved in ethyl acetate, and an aliquot is analyzed by GLC on a 3% OV-17 column. The extraction recovery from spiked plasma was 93.2 +/- 2.1% (SD), whereas linearity for the overall procedure was in the 0-1-microgram/ml range. The detection limit of the thermionic nitrogen detector was 50 ng/ml. The within-run and within days precision (CV) were 4.0 and 6.2%, respectively, at 300 ng/ml.