title: The quantitation of cyclophosphamide in human blood and urine by mass spectrometry-stable isotope dilution.
abstract: The levels of cyclophosphamide in the blood and the urine of patients have been monitored by direct insertion, electron impact mass spectrometry using the principle of stable isotope dilution. When a tetradeuterated analogue of the drug was added to a sample of blood or urine the concentration of cyclophosphamide could be determined from the ratio of the intensities of the signals (M-CH2 C1) characteristic for cyclophosphamide and the tetradeuterated analogue present in the mass spectrum of a chloroform extract. The procedure is highly specific for cyclophosphamide and obviates the need to use radioactively labelled cyclophosphamide for quantitation of the drug in man.
mesh_terms: D018288:Carcinoma, Small Cell / Q000188:drug therapy; D002845:Chromatography; D003520:Cyclophosphamide / Q000032:analysis* / Q000097:blood / Q000627:therapeutic use / Q000652:urine; D003903:Deuterium; D006801:Humans; D007201:Indicator Dilution Techniques; D007553:Isotope Labeling; D008175:Lung Neoplasms / Q000188:drug therapy; D013058:Mass Spectrometry; D008722:Methods
chemical_list: D003520:Cyclophosphamide; D003903:Deuterium