Simultaneous determination of irinotecan and its metabolite 7-ethyl-10-hydroxycamptothecin in biological fluids using excitation-emission matrix fluorescence coupled with second-order calibration method

Abstract

Irinotecan (CPT-11) belongs to the class of topoisomerase I inhibitors, which is an anticancer agent widely employed in the treatment of colorectal, lung, cervical, and ovarian cancer. 7-Ethyl-10-hydroxycamptothecin (SN38) is a main metabolite of CPT-11 in human body, which is approximately 100~1000-fold more cytotoxic than the parent drug. Several analytical techniques such as HPLC, LC-MS/MS have been proposed for determination of CPT-11 and SN38 in biological samples. But all of these methods are not only expensive, but also involve careful sample pretreatment or rigorous liquid chromatographic separation steps when conducting the experiments in the practical application. In this paper, a new and effective strategy that combines the excitation-emission matrix fluorescence (EEMF) with second-order calibration method based on alternating normalization-weighted error (ANWE) algorithm was developed for simultaneous determination of CPT-11 and SN38 in body fluids including human plasma and urine samples. Although the fluorescence spectra of CPT-11 and SN38 overlapped and unknown and uncalibrated fluorescent components coexisted in the matrices, the methodology enables accurate concentrations together with reasonable resolution of excitation and emission profiles for the compounds of interest, which is often referred to as the "second-order advantage". The assay was linear over the concentration range of 0.0141~0.0987 μg/mL for CPT-11 and 0.04~0.28 μg/mL for SN 38, respectively. When the component number was chosen to 3, the obtained average recoveries were (96.8±6.3)% and (101.7±1.1)% for CPT11, (100.4±4.9)% and (101.6±1.1)% for SN38 in plasma and urine, respectively. In order to evaluate the performances of the proposed approach, the figures of merit such as sensitivity, selectivity, limit of detection and limit of quantification were investigated. The satisfactory qualitative and quantitative results indicated that it is an attractive alternative strategy for the routine resolution and quantification of CPT-11 and its metabolite SN 38 even in the presence of unknown interferences or when complete separation is not easily achieved. © 2013 Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences.