Evaluation of a Procedure for the Simultaneous Quantification of 4-Ketocyclophosphamide, Cyclophosphamide, and Ifosfamide in Human Urine

An accurate and precise analysis procedure is presented for the detection and quantification of cyclophosphamide (CP), 4- ketocyclophosphamide (4-keto-CP), a primary metabolite of CP, and ifosfamide (IF) in human urine. CP and IF are common antineoplastic drugs used for the treatment of many types of cancer. Workers in the healthcare field, including nurses and pharmacists who interact with or prepare prescriptions for patients, have potential low-level exposure to the parent drugs; therefore, an analysis procedure is needed. The main focus of this procedure is the quantitation of 4-keto-CP because it is a primary metabolite of CP exposure and stable under physiological conditions. Sample preparation consists of liquid-liquid extraction of urine with ethyl acetate, and the analysis consists of reversed-phase highperformance liquid chromatography coupled with tandem mass spectrometry for detection of the analytes. Accuracy and precision of this procedure is demonstrated by means of recovery experiments. Recoveries are between 97-105% of theory for the three target analytes at various concentrations (25, 50, 100, and 375 ng/mL for 4-keto-CP; 1, 2, 4, and 15 ng/mL for CP and IF) with relative standard deviations of 8.4% or less. The limit of detection for this procedure is 1 ng/mL for 4-keto-CP, 0.1 ng/mL for CP, and 0.05 ng/mL for IF in urine.