Rapid and Sensitive Method for Determination of Cyclophosphamide in Patients Plasma Samples Utilizing Microextraction by Packed Sorbent Online with Liquid Chromatography‐Tandem Mass Spectrometry (MEPS‐LC‐MS/MS)

Abstract

The aim of the present investigation was to develop a simple and fast method for the determination of cyclophosphamide in human plasma samples. Microextraction in packed syringe (MEPS) was used as an online rapid sample preparation method, followed by liquid chromatography with tandem mass spectrometry (LC‐MS‐MS) for the quantification of cyclophosphamide. The new method reduced the sample handling and the analysis time by several folds compared to liquid chromatography and UV detection. The limit of detection (LOD) was 0.005 µg/mL and the lower limit of quantification was 0.5 µg/mL. The accuracy of the quality control (QC) samples ranged from 95 to 106%. The inter‐day variation was within the range 5–9% while the intra day variation was between 1–5%. The calibration curve in plasma was constructed within the concentration range 0.5–150 µg/mL. The regression correlation coefficient (r) was ≥0.99 for all runs. The limit of detection improved by 100 time using MEPS‐LC‐MS/MS (0.005 µg/mL) compared to LLE‐LC‐UV (0.5 µg/mL). The present method was employed for the analysis of human plasma samples for more 170 patient samples. The concentrations obtained from LC‐MS‐MS were in good agreement with these obtained from LC‐UV with the ratio of 1.02±0.11. The present method is rapid, reliable, and robust and may be used for therapeutic drug monitoring of cyclophosphamide.