A simple and rapid procedure to determine felbamate (2-phenyl-1,3-propanediol dicarbamate) concentrations in human plasma/serum by high-performance liquid chromatography is described. The method employs a high-performance liquid chromatography unit equipped with a C18 reverse-phase cartridge (3-micro;l particle diameter, 3.2 times; 40 mm), an acetonitrile/water gradient, and detection at 210 nm. The sample is deproteinized with acetonitrile containing internal standard (2-methyl-2-phenyl-1,3-propanediol dicarbamate), and the resulting supernatant, after diluting 1:1 with water, is injected onto the column. The felbamate and internal standard are eluted with a linear gradient of 0 to 22 acetonitrile for 11 minutes at a flow rate of 0.8 ml/minute. Under these conditions, felbamate and the internal standard are eluted at 9.2 plusmn; 0.03 and 10.8 plusmn; 0.03 minutes, respectively. The assay is linear from 10 to 400 micro;g/ml. It is highly reproducible; at 100 micro;g/ml felbamate, within-day and between-day coefficients of variation are less than 0.5 and 4.3, respectively. Recovery is ge;95. No interferences from other common antiepileptic drugs and analgesics are observed. Advantages of this method include simple and fast sample preparation; use of a gradient to eliminate interferences; and use of a cartridge column, which is economical, provides good resolution, allows rapid equilibration and elution, and operates at low back pressures. The method requires samples of only 100 micro;l and is ideal for pediatric samples.
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