Determination of chemotherapeutic drugs in human urine by capillary electrophoresis with UV and fluorimetric detection using solid‐supported liquid–liquid extraction for sample clean‐up

Capillary electrophoresis was used for the rapid determination of three chemotherapeutic drugs employed to treat colorectal cancer: irinotecan, tegafur, and leucovorin, and their main metabolites (7‐ethyl‐10‐hydroxycamptothecin and 5‐fluorouracil), in human urine samples. A phosphate buffer (pH 11.34; 20 mM) was selected as the background electrolyte. A hydrodynamic injection (9 s, 30 mbar) was applied and the separation was carried out using a separation temperature and voltage of 25°C and 25 kV, respectively. A capillary with two detection windows for serial online UV and fluorescence detection was satisfactorily employed. A solid‐supported liquid–liquid extraction procedure was optimized for the clean‐up of the urine samples and the extraction of the analytes. Matrix effects were assessed and signal suppression was observed for three of the analytes, thus, matrix‐matched calibration was used for compensating residual matrix effects on these analytes. The proposed method allows the separation and quantification of the chemotherapeutics in less than 6 min. Detection limits range between 0.01 and 0.30 mg/L. The method was satisfactorily applied to the determination of the target compounds in human urine samples, with recoveries of 92.4–107.7%.