Abstract
A simple and sensitive liquid chromatographic assay procedure using a fluorescence detector for the quantitative determination of verapamil in plasma without extraction was developed. After precipitating the protein with acetonitrile, the resulting supernatant liquid was injected onto the column for analysis. Chromatographic separation was achieved on C
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reversed phase column and the eluting solvent was the isocratic mixture of methanol, acetonitrile and pH 3.0 glycine buffer (1:4:5). With this mobile phase the drug and its internal standard were well separated from the interference of the plasma sample. The average recovery of verapamil from 3 replicate samples of different concentration (100-600 ng/mL) were 95.5 ± 5.68%. The minimum amount of verapamil detectable by this method was 40 ng/mL of sample. The elimination half-life (β-phase) of this drug in rabbits was found to be 3.7 hours.