Determination of the Camptothecin Derivatives CPT-11 and SN-38 in Urine and Saliva by Micellar Electrokinectic Chromatography

Abstract

The anti-cancer synthetic drug irinotecan (CPT-11) and its active metabolite SN-38 have been determined by micellar electrokinetic capillary chromatography (MEKC). The detection of the analytes was made at 368 nm and their separation took less than 7 min using a borate buffer (pH 8.8 at 25 mmol L⁻¹) solution containing sodium dodecyl sulfate (45 mmol L⁻¹) and acetonitrile (13.5% v/v). On-line analyte concentration (normal stacking mode) and the use of a highly sensitive cell (Z shaped cell) improved detection limits (at the 10⁻⁸ mol L⁻¹ level). Recovery in fortified human saliva was 108 ± 5%, in agreement with the result achieved with the reference HPLC method. For the analysis of urine from rats submitted to a single dose of CPT-11 and SN-38, camptothecin was used as internal standard enabling recoveries close to 100% when compared to the results achieved using HPLC.

Keywords:

• Irinotecan
• Micellar electrokinetic capillary chromatography
• Normal stacking mode
• SN-38

Acknowledgments

Financial support from the Brazilian agencies FAPERJ and FINEP is acknowledged. R. Q. Aucelio thanks CNPq and FAPERJ for scholarships. F. F. C. Marques thanks FAPERJ for a scholarship. The authors thank Statsoft-Brazil for the statistical package (Statistica 7.0). M. Vianna, M. Sci.; A. M. Miguel, Vet. M.D.; and the technician F. Pereira are acknowledged for dealing with the rats (administration of drugs and collection of samples). The authors are grateful for the biotery facilities and animals made available by Dr. J. Landeira (Clinical and Experimental Neuropsychology Group).

Notes

Note. Sample solution: water: pH 8.8 borate buffer 25 mmol L⁻¹ (pH 8.8), 1:3 (v/v).

BGE: pH 8.8 borate buffer (25 mmol L⁻¹), 50 mmol L⁻¹ of SDS, ACN 13.5% v/v.

Instrumental parameters: Temperature of 25°C; Applied voltage of 25 kV; Hydrodynamic sample injection at 50 mbar for 75 s; Detection at 368 nm in a 1200 µm in the detection window.

^a Average of 3 curves.

^b Evaluated as repeatability (n = 6).

^c 3s/m.

^d 10s/m.