Determination of isosorbide-5-mononitrate in human plasma by high-resolution gas chromatography

A method for the determination of isosorbide-5-mononitrate (5-ISMN) in human plasma by capillary gas chromatography with electron-capture detection was developed and applied to clinical samples. 9-Fluorenone was used as an internal standard, ethyl acetate was employed for liquid–liquid extraction. The advantage of the extraction procedure is the possibility of a direct injection of the plasma extract, without solvent removal/reconstitution of the sample. The precision and accuracy of the method were satisfactory in the concentration range 10–1600 ng/ml. The lower limit of quantification was 10 ng/ml.