Determination of unchanged hydralazine in plasma by gas-liquid chromatography using nitrogen-specific detection

A gas chromatographic method is described for the specific determination of unchanged hydralazine in plasma. On treatment with 2,4-pentanedione, hydralazine is converted into 1-(3,5-dimethyl-1-pyrazolyl)phthalazine, a stable compound which is easily extracted from biological material and determined quantitatively by gas chromatography with nitrogen-specific detection. 4-Methylhydralazine is used as an internal standard. The sensitivity of the method is ca. 10 ng/ml. Hydrazones of hydralazine do not interfere with the assay.